Chapter 2. The MIT, BSD, Apache, and Academic Free Licenses

The MIT and BSD Licenses were two of the earliest open source licenses. Because these licenses are relatively straightforward and illustrate some of the basic principles of open source licensing, they are described here first. The MIT (or X), BSD, and Apache Licenses are classic open source licensing software licenses and are used in many open source projects. The most well-known of these are probably the BSDNet and FreeBSD Unix-like operating systems and the Apache HTTP Server.

These licenses, as applied to the original licensed code, allow that code to be used in proprietary software and do not require that open source versions of the code be distributed. Code created under these licenses, or derived from such code, may go “closed” and developments can be made under that proprietary license, which are lost to the open source community. For the same reason, however, these licenses are very flexible and compatible with almost every form of open source license.

Tip

If you’re interested in licenses that keep code from being used in proprietary software, look ahead to Chapter 3.

The Academic Free License is a somewhat more elaborate license, embodying many of the same provisions found in the MIT, BSD, and Apache Licenses; in addition, it includes certain clauses addressing the application of patent rights to open source software.

The MIT (or X) License

The MIT License, the simplest license in this book, begins as follows:

Copyright (c) <year> <copyright holders>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The <year> and <copyright holder> tags obviously refer to the date of publication of the code and the person in whom copyright is vested, which is generally going to be the creator of the code. This part of the license essentially surrenders all of the rights that the copyright holder typically receives, including, as discussed in the previous chapter, the exclusive right to commercially exploit the work and to develop derivative works from the work. In addition, the licensee may, but need not, permit its own licensees to exercise these same rights.

This grant of rights is subject to two conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

And:

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. [all caps in original]

The first of these two conditions is almost universal in open source licensing and serves the straightforward and necessary purpose of alerting future users of the work of the restrictions on it. (Copyright laws used to require that copyrighted works carry an explicit notice in published forms to receive copyright protection.) The second of the two conditions provides the warranty disclaimer described in the previous chapter.

The BSD License

The BSD License, which is only slightly more restrictive than the MIT License, exists in a number of substantially similar forms. The following example is the UCB/LBL form, named after the University of California at Berkeley and the Lawrence Berkeley Laboratory.

This license, like the MIT License, begins:

Copyright (c) <YEAR>, <OWNER>

All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

The copyright notice and the attribution are substantially the same as those in the MIT License. Again, the license should reflect the actual year of copyright and the correct name of the creator.

Prior to 1999, the BSD License contained the following provision:

All advertising materials mentioning features or use of this software must display the following acknowledgement: This product includes software developed by the University of California, Lawrence Berkeley Laboratory.

This provision seems relatively innocuous. It seems both reasonable and natural that the creator, having surrendered the exclusive right to commercially exploit a work, should receive credit not only in the acknowledgment of rights but in the advertising as well. It does not challenge the essential premises of open source, as it does not limit the scope of the use of the software in any direct way. Nonetheless, the pre-1999 BSD License sometimes causes problems because of this clause. The principles of open source endorse the commercial exploitation of software, including the sale of software, manuals, and support for profit. Such commercial exploitation very well may include advertising and when an open source project draws from a number of predecessors, the requirement of including such references can become a real burden. The BSD License, however, was amended in 1999 and this clause was removed. The University of California rescinded this clause and to the extent it may still be found in BSD files licensed by the University of California, it no longer has any legal effect.

The remainder of the license largely mirrors the effect of the provisions of the MIT License already described, by conditioning distribution—whether in modified form or not—on the maintenance of the conditions already described:

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

Neither the name of the <ORGANIZATION> nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

With the clause about advertising removed (formerly, the third clause in the license), the only substantial difference between this license and the MIT License is the non-attribution provision in the last clause. This provision requires prior permission for use of the name of the creator, and it protects the reputation of the creator from being explicitly associated with derivative versions of the program. Such restrictions permit creators to protect themselves from the injury to their reputations that can result from association with a defective or poorly written program, while still allowing others to use or modify a work.

The final provision is a disclaimer of warranties:

THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS “AS IS” AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

This provision specifically disclaims any express warranty, as well as the warranties of merchantability and fitness for a particular purpose, and it operates much like the disclaimer in the MIT License.

The Apache License, v1.1 and v2.0

The Apache License is very similar to the BSD and MIT Licenses already described. The Apache License, Version 1.1, follows substantially the same pattern as the BSD License in premising distribution and modification upon compliance with relatively unrestrictive terms. Version 2.0, a top-down rewriting of the license, was first published in 2004 and is described in detail later.

The Apache License, v1.1

Version 1.1 is slightly longer than the licenses discussed earlier in the chapter, but it operates in much the same way.

Copyright (c) 2000 The Apache Software Foundation.

All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

The copyright notice, the clause introducing the limitations on distribution, and the first two limitations are substantially identical to those in the BSD License.

3. The end-user documentation included with the redistribution, if any, must include the following acknowledgment: “This product includes software developed by the Apache Software Foundation (http://www.apache.org/).”

Alternately, this acknowledgment may appear in the software itself, if and wherever such third-party acknowledgments normally appear.

The Apache License does not have the cumbersome advertising clause in the rescinded version of the BSD License, but it requires an acknowledgment of the creator’s contribution to the work being distributed.

4. The names “Apache” and “Apache Software Foundation” must not be used to endorse or promote products derived from this software without prior written permission. For written permission, please contact apache@apache.org.

Like the BSD License, the Apache License contains a non-attribution provision, which protects the reputation of the creator.

5. Products derived from this software may not be called “Apache” nor may “Apache” appear in their name, without prior written permission of the Apache Software Foundation.

Like the provision just discussed, this provision prevents the possibly damaging association of the creator with derivative works created from the original code.

Finally, the Apache License includes a warranty disclaimer provision substantially similar to those already described.

THIS SOFTWARE IS PROVIDED “AS IS” AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

The license closes with clauses identifying the contributors to the code being distributed. These are not, strictly speaking, parts of the license as they impose no obligation on the user.

This software consists of voluntary contributions made by many individuals on behalf of the Apache Software Foundation. For more information on the Apache Software Foundation, please see <http://www.apache.org/>.

Portions of this software are based upon public domain software originally written at the National Center for Supercomputing Applications, University of Illinois, Urbana-Champaign.

The Apache License, v2.0

Released in January, 2004, the Apache License, v2.0, is a thorough revision of the Apache License. While the Apache License, v1.1, operates much like a BSD or MIT License with a non-endorsement provision barring the use of the Apache name without permission, v2.0 is a fuller and more complex license, laying out in more specific detail the rights granted. In particular, v2.0 differs in that it expressly addresses both patent rights being granted by the license and the use of other licenses for derivative works based on works licensed under v2.0. Perhaps most importantly, v2.0 provides for “Contributions” to the licensed work that are made with the express understanding that they will become part of the licensed work and will be governed by v2.0.

After the introductory phrases, definitions appear.

Apache License

Version 2.0, January 2004

http://www.apache.org/licenses/

TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

1. Definitions.

“License” shall mean the terms and conditions for use, reproduction and distribution as defined by Sections 1 through 9 of this document.

“Licensor” shall mean the copyright owner or entity authorized by the copyright owner that is granting the License.

These terms are both self-explanatory. The “License” is this document. The Licensor is that person with ability and inclination to grant the rights described in the License.

“Legal Entity” shall mean the union of the acting entity and all other entities that control, are controlled by, or are under common control with that entity. For the purposes of this definition, “control” means (i) the power, direct or indirect, to cause the direction or management of such entity, whether by contract or otherwise, or (ii) ownership of fifty percent (50%) or more of the outstanding shares, or (iii) beneficial ownership of such entity.

“Legal Entity”, substantially similar to the Mozilla Public License described in the next chapter, provides that complexly structured organizations, such as many large corporations, are considered to be one entity for the purposes of this license.[1]

“You” (or “Your”) shall mean an individual or Legal Entity exercising permissions granted by this License.

“You” is equivalent to the licensee, i.e., the party that is bound by the license.

“Source” form shall mean the preferred form for making modifications, including but not limited to software source code, documentation source, and configuration files.

This definition is a slightly more expansive form of the term “source code,” expanded to include documentation, source, and configuration, including all information necessary or useful in modifying or creating a derivative work from a piece of code.

“Object” form shall mean any form resulting from mechanical transformation or translation of a Source form, including but not limited to compiled object code, generated documentation, and conversions to other media types.

This definition is also a more expansive form of what is generally referred to as the executable form of code, compiled so that, when run, the code performs a function or functions.

“Work” shall mean the work of authorship, whether in Source or Object form, made available under the License, as indicated by a copyright notice that is included in or attached to the work (an example is provided in the Appendix below).

This term “Work” is substantially similar to work as that term is used in copyright law and throughout this book. “Work” is the copyrighted work that is the subject of the license.

“Derivative Works” shall mean any work, whether in Source or Object form, that is based on (or derived from) the Work and for which the editorial revisions, annotations, elaborations, or other modifications represent, as a whole, an original work of authorship. For the purposes of this License, Derivative Works shall not include works that remain separable from, or merely link (or bind by name) to the interfaces of, the Work and Derivative Works thereof.

This definition, " Derivative Works,” is also substantially similar to the term derivative work as used in copyright law and in this book. It means a work that is a modification of or otherwise derived from the original work. This definition excludes certain combinations of works: when another work merely links to the interfaces of the “Work” it does not become a “Derivative Work,” as that term is used in this license. This is an important distinction, as specific limitations apply under the License to Derivative Works, explained later.

“Contribution” shall mean any work of authorship, including the original version of the Work and any modifications or additions to that Work or Derivative Works thereof, that is intentionally submitted to Licensor for inclusion in the Work by the copyright owner or by an individual or Legal Entity authorized to submit on behalf of the copyright owner. For the purposes of this definition, “submitted” means any form of electronic, verbal, or written communication sent to the Licensor or its representatives, including but not limited to communication on electronic mailing lists, source code control systems, and issue tracking systems that are managed by, or on behalf of, the Licensor for the purpose of discussing and improving the Work, but excluding communication that is conspicuously marked or otherwise designated in writing by the copyright owner as “Not a Contribution.”

A "Contribution” is a specific modification to the Work that is provided to the original Licensor for the explicit purpose of being included in the Work. A Licensee under the License may choose to modify the Work and to create a separate Derivative Work subject to the terms of the License. A licensee may also choose to submit that modification to the Licensor in the form of a Contribution, and, if accepted, that Contribution becomes part of the original Work, under the copyright and control of the Licensor. The original work with any such “Contributions,” obviously, will continue to be licensed under v2.0.

“Contributor” shall mean Licensor and any individual or Legal Entity on behalf of whom a Contribution has been received by Licensor and subsequently incorporated within the Work.

This is a common sense reflection of Contribution: a Licensee who makes a Contribution is a Contributor. The original Licensor is also a Contributor, as that term is used in the License.

2. Grant of Copyright License.

Subject to the terms and conditions of this License, each Contributor hereby grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare Derivative Works of, publicly display, publicly perform, sublicense, and distribute the Work and such Derivative Works in Source or Object form.

This provision is, as described in its title, the grant of copyright license. The license granted is irrevocable and royalty free and grants Licensees all the rights available under copyright, including the right to reproduce and distribute the Work and Derivative Works. As part of making a Contribution, a Contributor has consented to making a grant of rights as to the Contribution on the same terms as the original Work.

Unlike the BSD, MIT, and the Apache License, v1.1, the Apache License, v2.0, also explicitly grants rights under a patent claims that may exist in the original Work.

3. Grant of Patent License.

Subject to the terms and conditions of this License, each Contributor hereby grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable (except as stated in this section) patent license to make, have made, use, offer to sell, sell, import, and otherwise transfer the Work, where such license applies only to those patent claims licensable by such Contributor that are necessarily infringed by their Contribution(s) alone or by combination of their Contribution(s) with the Work to which such Contribution(s) was submitted. If You institute patent litigation against any entity (including a cross-claim or counterclaim in a lawsuit) alleging that the Work or a Contribution incorporated within the Work constitutes direct or contributory patent infringement, then any patent licenses granted to You under this License for that Work shall terminate as of the date such litigation is filed.

This patent license only grants the irrevocable, royalty-free license to the extent that such patent rights are necessary to use the original Work (and Contributions thereto). This grant does not extend to patent rights that may inhere in the Work separate and apart from the Work itself. Like the Academic Free License, described in the next section, in the event that a Licensee initiates patent litigation against any Contributor on the basis that any part of the Work infringes on a patent, the License terminates as to that Licensee as of the date that litigation is filed. This prevents the situation in which a party is getting the benefit of the rights to the Work under the License while at the same time suing the Licensor or Contributor under a claim of patent infringement.[2]

Redistribution of the Work or Derivative Works created by the licensee therefrom is permitted to that licensee subject to certain, relatively limited, restrictions.

4. Redistribution.

You may reproduce and distribute copies of the Work or Derivative Works thereof in any medium, with or without modifications, and in Source or Object form, provided that You meet the following conditions:

1. You must give any other recipients of the Work or Derivative Works a copy of this License; and

2. You must cause any modified files to carry prominent notices stating that You changed the files; and

3. You must retain, in the Source form of any Derivative Works that You distribute, all copyright, patent, trademark, and attribution notices from the Source form of the Work, excluding those notices that do not pertain to any part of the Derivative Works; and

4. If the Work includes a “NOTICE” text file as part of its distribution, then any Derivative Works that You distribute must include a readable copy of the attribution notices contained within such NOTICE file, excluding those notices that do not pertain to any part of the Derivative Works, in at least one of the following places: within a NOTICE text file distributed as part of the Derivative Works; within the Source form or documentation, if provided along with the Derivative Works; or, within a display generated by the Derivative Works, if and wherever such third-party notices normally appear. The contents of the NOTICE file are for informational purposes only and do not modify the License. You may add Your own attribution notices within Derivative Works that You distribute, alongside or as an addendum to the NOTICE text from the Work, provided that such additional attribution notices cannot be construed as modifying the License.

These terms give fair notice to the licensee’s distributees—those people receiving a copy of the Work or a Derivative Work from a licensee—of the terms of the license applicable to the Work; the modifications, if any, made to the Work; the copyright, patent, and trademark notices present in the original Work; and, if applicable, the Notice file distributed with the Work.

The last paragraph of this section makes explicit what is implicit in the MIT, BSD, and Apache License, v1.1, which is that the creator of a Derivative Work based on the Work may license that Derivative Work under a license other than that applicable to the original work.

You may add Your own copyright statement to Your modifications and may provide additional or different license terms and conditions for use, reproduction, or distribution of Your modifications, or for any such Derivative Works as a whole, provided Your use, reproduction, and distribution of the Work otherwise complies with the conditions stated in this License.

The application of different license terms (which may include proprietary license terms) is permitted so long as the terms of that license comply with the License. There is no requirement that the Licensor of such a Derivative Work make available the source code for the Derivative Work or otherwise license it under an open source or free software license.

5. Submission of Contributions.

Unless You explicitly state otherwise, any Contribution intentionally submitted for inclusion in the Work by You to the Licensor shall be under the terms and conditions of this License, without any additional terms or conditions. Notwithstanding the above, nothing herein shall supersede or modify the terms of any separate license agreement you may have executed with Licensor regarding such Contributions.

This section makes clear what was implicit in the definition of Contribution already described. By making a Contribution, the Contributor agrees that the Contribution shall be governed by the terms of the License unless another, specific agreement is made with the Licensor.

6. Trademarks.

This License does not grant permission to use the trade names, trademarks, service marks, or product names of the Licensor, except as required for reasonable and customary use in describing the origin of the Work and reproducing the content of the NOTICE file.

As was the case with the Apache License, v1.1, licensees are not granted any trademark rights and are prohibited from associating the name of the Licensor with their Derivative Works (or their distribution of the original Work), except as necessary to give notice of the source of the work.

7. Disclaimer of Warranty.

Unless required by applicable law or agreed to in writing, Licensor provides the Work (and each Contributor provides its Contributions) on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied, including, without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. You are solely responsible for determining the appropriateness of using or redistributing the Work and assume any risks associated with Your exercise of permissions under this License.

8. Limitation of Liability.

In no event and under no legal theory, whether in tort (including negligence), contract, or otherwise, unless required by applicable law (such as deliberate and grossly negligent acts) or agreed to in writing, shall any Contributor be liable to You for damages, including any direct, indirect, special, incidental, or consequential damages of any character arising as a result of this License or out of the use or inability to use the Work (including but not limited to damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses), even if such Contributor has been advised of the possibility of such damages.

These two provisions operate the same way as those provisions in the MIT, BSD, and Apache License, v1.1, in disclaiming warranties and limiting liabilities, except under circumstances where a Contributor has explicitly undertaken to provide a warranty.

9. Accepting Warranty or Additional Liability.

While redistributing the Work or Derivative Works thereof, You may choose to offer, and charge a fee for, acceptance of support, warranty, indemnity, or other liability obligations and/or rights consistent with this License. However, in accepting such obligations, You may act only on Your own behalf and on Your sole responsibility, not on behalf of any other Contributor, and only if You agree to indemnify, defend, and hold each Contributor harmless for any liability incurred by, or claims asserted against, such Contributor by reason of your accepting any such warranty or additional liability.

This section explicitly permits a licensee to enter into a separate warranty arrangement with others for the Work or Derivative Works. This makes clear what is implicit in Sections 7 and 8, that such a warranty obligation only extends to the party making that warranty and not to any Contributor. Any licensee making such a warranty agrees to “indemnify, defend, and hold harmless” any Contributor in connection with any claim against such a Contributor. This means that the party giving the warranty agrees to pay any and all costs associated with defending such a claim, including attorney’s fees and the costs of paying a judgment, if a judgment is entered against such a Contributor.

Following the end of the “terms and conditions” is a short appendix with a boilerplate notice indicating that a given Work is subject to the terms of this License.

The Apache License, v2.0, operates substantially like the MIT, BSD, and Apache License, v1.1, with some additional benefits. First, it makes clear that the licensing of Derivative Works under other licenses is permitted so long as the terms of the Apache License, v2.0, are complied with. This is implied but not specifically spelled out in the MIT and BSD Licenses. Second, the Apache License, v2.0, provides clearly marked pathways for both open development and non-open development of code licensed under it. By making a Contribution, a licensee is agreeing to have that addition to the Work licensed under the same, open, terms applicable to the original Work. Particularly for dynamic well-organized open developments like Apache, this is likely a common result for modifications to the Work. But there is no obligation to make a Contribution: licensees are free to take their Derivative Work and license it under a different license. While this approach does not resolve the tension between open and closed development of software, at least it makes what the options are clear.

The Academic Free License

The Academic Free License is substantially similar to the Apache License, v1.1, in forbidding claims of endorsement by the work’s creator, in requiring attribution to the creator, in disclaiming warranties, and in permitting distribution of the original work and derivative works subject only to certain limitations. The Academic Free License adds four more provisions that are not in the Apache or BSD Licenses, two of them pertaining to patent law, and two of them governing choice of law and shifting of attorneys fees.

As discussed in Chapter 1, the intellectual property rights at play in software licenses derive for the most part from copyright, protecting the expression of particular ideas. The Academic Free License also addresses the case in which a patent holder chooses to permit the open source use of that patent.

Paragraph 1 of the Academic Free License (v2.0) provides:[3]

1) Grant of Copyright License. Licensor hereby grants You a world-wide, royalty-free, non-exclusive, perpetual, sublicenseable license to do the following: a) to reproduce the Original Work in copies; b) to prepare derivative works (“Derivative Works”) based upon the Original Work; c) to distribute copies of the Original Work and Derivative Works to the public; d) to perform the Original Work publicly; and e) to display the Original Work publicly.

This is essentially the same bundle of rights granted by the Apache and BSD Licenses already discussed. Paragraph 2 distinguishes the Academic License by making it clear that patent claims owned or controlled by the Licensor are licensed to those working with this software.

2) Grant of Patent License. Licensor hereby grants You a world-wide, royalty-free, non-exclusive, perpetual, sublicenseable license, under patent claims owned or controlled by the Licensor that are embodied in the Original Work as furnished by the Licensor, to make, use, sell and offer for sale the Original Work and Derivative Works.

This paragraph grants the licensee a license to exercise patent rights without payment of royalties, so long as a) those patent rights are held by the licensor, and b) those patent rights are exercised in connection with the Original Work or a Derivative Work. Accordingly, this may be an appropriate license (or license provision) to be used for a work that its creator intends to be open source licensed that includes property subject to one or more patents.

While this license explicitly provides for the granting of rights under both copyright and patent, some of the licenses previously described in this book (and some of the ones that follow) implicitly provide such a grant. Because the granting of patent rights involves a number of issues distinct from those in granting rights under copyright law, you may want to review the discussion of patents in Chapter 1.

Paragraph 3 of the license states that the Licensor will make the source code of the licensed program available in some form, a term that is common to the open source licenses described later in this book.

3) Grant of Source Code License. The term “Source Code” means the preferred form of the Original Work for making modifications to it and all available documentation describing how to modify the Original Work. Licensor hereby agrees to provide a machine-readable copy of the Source Code of the Original Work along with each copy of the Original Work that Licensor distributes. Licensor reserves the right to satisfy this obligation by placing a machine-readable copy of the Source Code in an information repository reasonably calculated to permit inexpensive and convenient access by You for as long as Licensor continues to distribute the Original Work, and by publishing the address of that information repository in a notice immediately following the copyright notice that applies to the Original Work.

Paragraph 4 of the license delineates the limitations of the license and includes a non-endorsement provision similar to the one in the Apache License.

4) Exclusions From License Grant. Neither the names of Licensor, nor the names of any contributors to the Original Work, nor any of their trademarks or service marks, may be used to endorse or promote products derived from this Original Work without express prior written permission of the Licensor. Nothing in this License shall be deemed to grant any rights to trademarks, copyrights, patents, trade secrets or any other intellectual property of Licensor except as expressly stated herein. No patent license is granted to make, use, sell or offer to sell embodiments of any patent claims other than the licensed claims defined in Section 2. No right is granted to the trademarks of Licensor even if such marks are included in the Original Work. Nothing in this License shall be interpreted to prohibit Licensor from licensing under different terms from this License any Original Work that Licensor otherwise would have a right to license.

5) This section intentionally omitted.

Paragraph 5 speaks for itself. Paragraph 6 requires attribution of the Licensor in the source code of any derivative works. The utility of this paragraph is limited by the fact that the Academic License may not, as explained later, require Licensees to distribute source code along with derivative works.

6) Attribution Rights. You must retain, in the Source Code of any Derivative Works that You create, all copyright, patent or trademark notices from the Source Code of the Original Work, as well as any notices of licensing and any descriptive text identified therein as an “Attribution Notice.” You must cause the Source Code for any Derivative Works that You create to carry a prominent Attribution Notice reasonably calculated to inform recipients that You have modified the Original Work.

Paragraphs 7 and 8 disclaim warranties and limit liabilities in ways substantially similar to provisions in the MIT, BSD, and Apache Licenses. The first full sentence of Paragraph 7 explicitly warrants that the copyright and patent rights granted by the Licensor are owned by the Licensor.

7) Warranty of Provenance and Disclaimer of Warranty. Licensor warrants that the copyright in and to the Original Work and the patent rights granted herein by Licensor are owned by the Licensor or are sublicensed to You under the terms of this License with the permission of the contributor(s) of those copyrights and patent rights. Except as expressly stated in the immediately proceeding sentence, the Original Work is provided under this License on an “AS IS” BASIS and WITHOUT WARRANTY, either express or implied, including, without limitation, the warranties of NON-INFRINGEMENT, MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY OF THE ORIGINAL WORK IS WITH YOU. This DISCLAIMER OF WARRANTY constitutes an essential part of this License. No license to Original Work is granted hereunder except under this disclaimer.

8) Limitation of Liability. Under no circumstances and under no legal theory, whether in tort (including negligence), contract, or otherwise, shall the Licensor be liable to any person for any direct, indirect, special, incidental, or consequential damages of any character arising as a result of this License or the use of the Original Work including, without limitation, damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses. This limitation of liability shall not apply to liability for death or personal injury resulting from Licensor’s negligence to the extent applicable law prohibits such limitation. Some jurisdictions do not allow the exclusion or limitation of incidental or consequential damages, so this exclusion and limitation may not apply to You.

The next paragraph, Paragraph 9, is an example of a license provision imposing, or attempting to impose, a generational limitation that puts substantial limitations on the licensing of derivative works, as opposed to requiring an attribution or prohibiting putative endorsements. Because of ambiguous drafting, it is not immediately apparent what this paragraph is attempting to accomplish, but it appears that the requirement that it imposes on licensees to ensure that licensees of their own, derivative, works are similarly bound is not as stringent as that of other licenses discussed later in this book. The paragraph begins:

9) Acceptance and Termination. If You distribute copies of the Original Work or a Derivative Work, You must make a reasonable effort under the circumstances to obtain the express assent of recipients to the terms of this License.

There are problems with this first sentence. First, it is not immediately clear that the licensor intends that the provisions of this license also govern the derivative works created by the licensee and derivative works created by the licensee’s licensees and so forth. This sentence should probably be interpreted to mean that licensees assent to the proposition that the original work is in fact governed by the license; not necessarily that any derivative work be governed by the terms of that license. Second, and perhaps no less importantly, this sentence requires only that the licensee use “reasonable effort under the circumstances” to obtain assent of future licensees to the terms of the license, with regard both to the original and derivative works. A putative licensee, even one generation removed, could argue that because a previous licensee had not communicated these restrictions, the putative licensee believed that the work was bound by fewer than all the restrictions of the license or by no restrictions at all. The following sentence attempts to address this second problem.

Nothing else but this License (or another written agreement between Licensor and You) grants You permission to create Derivative Works based upon the Original Work or to exercise any of the rights granted in Section 1 herein, and any attempt to do so except under the terms of this License (or another written agreement between Licensor and You) is expressly prohibited by U.S. copyright law, the equivalent laws of other countries, and by international treaty.

As already noted, the statutory rights created by copyright bar any but limited use of a given work. The fact that a particular work is open source licensed does not remove its protection by the copyright laws. As the second sentence of this paragraph states, without the grant of rights by the license (along with the restrictions coupled thereto), no use of the copyrighted work is permitted. This “saves” the license and supports the argument that a putative licensee is bound by the terms of the license even if that licensee has not expressly assented to the terms of the license. Without some knowledge of the license, the putative licensee would have no reason to believe that he or she had any right at all to the work. Accordingly, such a putative licensee could be presumed to be “on notice” of the possibility of license restrictions and accordingly could be found to have legal liabilty for violating the terms of the license if he or she does not make sufficient efforts to determine the restrictions of the license. As discussed in Chapter 6, this provision, and similar ones in the licenses, is critical to the legal enforcement of open source licenses. The final sentence of this paragraph largely reiterates the effect of the second sentence: that use of the work is bound by the terms of the license and that exercise of rights under the license indicates consent to the restrictions imposed by it:

Therefore, by exercising any of the rights granted to You in Section 1 herein, You indicate Your acceptance of this License and all of its terms and conditions.

Paragraph 10 creates a disincentive for licensees to sue licensors for patent infringement. It is questionable how much this adds to the license, insofar as it seems unlikely that any person believing that he had or would have a legitimate claim for patent infringement against the creator of the work would use that work. Nonetheless, the license includes it, perhaps to avoid the unlikely, but undeniably awkward, situation in which the same person is suing the licensor and profiting in some manner from the use of the licensor’s work.

10) Termination for Patent Action. This License shall terminate automatically and You may no longer exercise any of the rights granted to You by this License as of the date You commence an action, including a cross-claim or counterclaim, for patent infringement (i) against Licensor with respect to a patent applicable to software or (ii) against any entity with respect to a patent applicable to the Original Work (but excluding combinations of the Original Work with other software or hardware).

The remainder of the license provisions consists largely of terms common to commercial contracts. Paragraph 11 provides for choice of the jurisdiction in which suits under the license may be brought:

11) Jurisdiction, Venue and Governing Law. Any action or suit relating to this License may be brought only in the courts of a jurisdiction wherein the Licensor resides or in which Licensor conducts its primary business, and under the laws of that jurisdiction excluding its conflict-of-law provisions. The application of the United Nations Convention on Contracts for the International Sale of Goods is expressly excluded. Any use of the Original Work outside the scope of this License or after its termination shall be subject to the requirements and penalties of the U.S. Copyright Act, 17 U.S.C. 101 et seq., the equivalent laws of other countries, and international treaty. This section shall survive the termination of this License.

In general, choice of venue and choice of law provisions specifically identify the court and law that govern. For example, a typical provision might specify that “Claims arising under this contract may only be brought before courts of competent jurisdiction within the State of New York. The law governing the resolution of such claims shall be the law of the State of New York without giving effect to the choice of laws provisions thereof.” Because of the open source nature of the license, however, and so that derivative works can be licensed under it without changing the text, the license tracks the jurisdiction in which suits can be brought (and the law that applies to the interpretation of the license) to follow the place in which the licensor resides or conducts its primary business. While this open-ended provision is somewhat problematic in that a licensee may face some uncertainty because the residence of a given licensor might be unknown to the licensee, it seems likely that this provision would likely be enforced by a court as long as the licensor’s residence could be readily determined.

Paragraph 12 contains a provision also fairly common in commercial contracts:

12) Attorneys Fees. In any action to enforce the terms of this License or seeking damages relating thereto, the prevailing party shall be entitled to recover its costs and expenses, including, without limitation, reasonable attorneys’ fees and costs incurred in connection with such action, including any appeal of such action. This section shall survive the termination of this License.

In all United States jurisdictions, parties to a suit bear their own costs for bringing the suit in most cases. Fee shifting provisions like this one, however, are generally enforced. While there is considerable debate about the social utility of this rule, known as the American rule (in contrast to the British rule, in which the prevailing party has historically been able to collect attorneys fees along with other damages), the balancing of the benefits of it are beyond the scope of this book. This provision is a fairly common one in contracts, but it has nothing to do with open source, except perhaps that it may encourage licensors to more vigorously pursue licensees who clearly violate the terms of a given license.

Paragraph 13 is also typical to commercial contracts, and it makes clear that the license is the only agreement between the parties.

13) Miscellaneous. This License represents the complete agreement concerning the subject matter hereof. If any provision of this License is held to be unenforceable, such provision shall be reformed only to the extent necessary to make it enforceable.

Such provisions, known as " merger clauses,” are generally included in contracts to make clear that pre-existing written agreements or oral agreements are superseded by the particular contract. This provision operates on an open source license as it would in any other agreement. The second sentence is a severability clause, preserving the effect of other sections of the license if a section is found to be invalid.

Paragraph 14 defines “You” as it is used in the license to include agents of the licensee or other persons within the control of the licensee.

14) Definition of “You” in This License. “You” throughout this License, whether in upper or lower case, means an individual or a legal entity exercising rights under, and complying with all of the terms of, this License. For legal entities, “You” includes any entity that controls, is controlled by, or is under common control with you. For purposes of this definition, “control” means (i) the power, direct or indirect, to cause the direction or management of such entity, whether by contract or otherwise, or (ii) ownership of fifty percent (50%) or more of the outstanding shares, or (iii) beneficial ownership of such entity.

This provision is probably not necessary. To the extent that any person or entity not under the control of a particular licensee exercises any of the rights described in Paragraph 1 of the license, they would likely be found to be directly bound by the license. The fact that they are associated with or controlled by another licensee would accordingly not matter.[4]

Finally, Paragraph 15 of the license provides that:

15) Right to Use. You may use the Original Work in all ways not otherwise restricted or conditioned by this License or by law, and Licensor promises not to interfere with or be responsible for such uses by You.

This paragraph adds no restrictions on licensees not already articulated by the license, but rather adds an additional restriction on the licensor, i.e., non-interference in uses permitted by the license. This is a somewhat problematic provision, as it could be interpreted to create legal liability for licensors in situations in which the drafter of this license probably did not intend to create liability. For example, a licensor whose work competes directly with that of a licensee could, at least in theory, be liable for “interference” with sales of the licensed work. While this is probably unlikely, it is not impossible that such a lawsuit could be maintained. It is almost certainly not the result contemplated by the drafter of the license.

The final un-numbered paragraph of the license sets out that while licensors can use the license, they cannot modify its terms without permission.

This license is Copyright (C) 2003 Lawrence E. Rosen. All rights reserved. Permission is hereby granted to copy and distribute this license without modification. This license may not be modified without the express written permission of its copyright owner.

Application and Philosophy

All of these licenses have been used in practice, both in licensing software maintained in the open source community and in providing the basis for commercial applications of programs derived from open source models. The BSD, MIT, and Apache Licenses, longer established and more frequently adopted than the Academic Free License, provide the examples described in this section.

Each of these three licenses has contributed to the widespread commercial adoption of the programs they license, frequently (though not always) through incorporation into products distributed under a proprietary license. This is completely consistent with the language and intent of the licenses. This also reflects their place of origin. For example, both Berkeley Unix and the X Window System were research projects; the goal of their creators was to explore technology, to provide a proof-of-concept implementation, and then to permit others to build on that work. Commercial applications readily followed successful implementations of research ideas.

BSD Unix became the basis for commercial versions of Unix ranging from Sun’s Solaris to Apple’s Mac OS X. BSD-derived proprietary versions of Unix outstripped the commercially licensed AT&T versions relatively quickly, and they dominated the commercial Unix market until the 1990s when Unix was challenged by GPL-licensed Linux distribution. The TCP/IP software stack that was part of the Berkeley networking release became the basis for almost all commercial TCP/IP stacks, including Microsoft’s. The X Window System became the standard GUI platform for the Unix workstation market, displacing Sun’s proprietary NeWS windowing system. In addition, even as these commercial implementations became available at the same time, open sourced implementations continued to be widely available and accessible for modifications and improvements by programmers.

Despite setbacks from a lawsuit from AT&T that was ultimately settled out of court in 1992, Berkeley Unix still has many million installations, running such well-known sites as Yahoo!, and it continues to be modified and improved. Moreover, and partly as a result, later commercial entrants such as Apple have tried to keep a better defined line between the open source foundations of their programs and their proprietary extensions.

Other individual parts of Berkeley Unix continued to flourish as parts of the free software ecosystem. For example BIND, the Berkeley Internet Name Daemon, continued to be maintained by its original author, Paul Vixie[5] under the auspices of the Internet Software Consortium. Despite many commercial implementations, the open source version of BIND continues to be the definitive version that runs the Internet’s Domain Name System (DNS), the single most mission-critical piece of software in the Internet infrastructure. Sendmail, another piece of Berkeley Unix, continues to be maintained by its creator, Eric Allman, who founded a company in 1998 to commercialize the software. He adopted a hybrid proprietary/open source strategy, completely consistent with the licenses, in which some new features of interest to commercial clients are released in proprietary software, while the open source version is also still maintained.

In short, research-style licenses, like the BSD and MIT Licenses, are ideal for situations in which you want wide deployment of your ideas and do not care whether this results in open source software or proprietary software. Because of their openness to commercial use, the programs they license can be, by many metrics, more influential. Red Hat maintains a Linux business that makes approximately $90 million in annual revenues, while Sun Microsystems has revenues of approximately $18 billion. There are literally billions of dollars of economic activity associated just with the Internet software stack originally released under the Berkeley License.

Nonetheless, the very success of the commercial developments premised on programs distributed under these licenses could be said to undermine the purpose of open source licensing. The argument could be made, for example, that the widespread adoption of commercial versions of such programs discourages open source development and encourages the creation of code closed off to the open source community by proprietary licenses. It could be regarded as a failure that the highly sophisticated Solaris software was developed as proprietary software,[6] that Microsoft was able to build a version of MIT’s Kerberos security software that contains proprietary extensions for communicating with Microsoft servers, or that Microsoft was able to build so easily on the Internet infrastructure software.

It cannot be said, however, that such a result is inconsistent with the text and the intent of these licenses or that such types of commercial uses were not foreseen by their drafters. The original BSD and X Window System developers intended their software to be used in this way. Some of these developers even built their own companies based on the open source software that they had originally written. Bill Joy was one of the founders of Sun Microsystems; Eric Allman was able to found Sendmail, Inc.

The one well-known case in which the software authors were unhappy with their choice was the licensing of the MIT Kerberos security program. As Microsoft appeared to embrace and extend Kerberos, the authors wished they had used a more stringent license like the GPL. Of course, in that case, Microsoft would have chosen another basis for their security software, and Kerberos would have been less widely used. Nonetheless, the authors may have reasonably felt that a more restrictive license might have better protected the development of the software that they had anticipated.

Moreover, at least for certain types of programs, the nature of the function performed by the software makes additional license restrictions unnecessary to maintain an open development model. The Apache license provides one such example. While there have been several proprietary commercializations of Apache (such as the SSL-enabled Stronghold), the free version of Apache has retained its dominant market share as the result of two dynamics:

  1. Strong branding. The Apache License’s requirement that derived works cannot use the Apache name gives a significant degree of protection.

  2. Standards-compliance. Because Apache is communications-oriented software, its need to adhere to standards such as the HTTP protocol prevents proprietary extensions. Of course, this protection remains only as long as Apache or other standards-compliant web servers retain dominant market share. Were Apache to lose its dominant market share, its protocols would no longer control, and this advantage would disappear.

These licenses, like all open source and free software licenses, permit forking and the subsequent fragmentation of projects. The multiple, and mutually incompatible, versions of BSD (FreeBSD, NetBSD, OpenBSD) provide one such example. However, this is less a result of the dynamic of the license itself than it is of the complex social dynamic involved in large software projects. The original BSD project leaders moved on to other activities, and the software was taken up by new people with different goals. This dynamic is discussed in more detail in Chapter 7.



[1] As discussed in Chapter 3, such a provision may simplify compliance by the licensee with the terms of the license but may not be enforceable in every case.

[2] This treatment of patent litigation renders v2.0 incompatible with the GNU General Public License described in the next chapter. See http://www.apache.org/licenses/GPL-compatibility.html.

[3] The text of the Acadmic License can be found at http://www.opensource.org/licenses/afl-2.0.php. It is copyright 2003 by Lawrence E. Rosen.

[4] This provision is discussed further in Chapter 3 in connection with the Mozilla Public License.

[5] The specifications for this program were written by Paul Mockapetris.

[6] Sun has recently announced that it will release Solaris under an open source license, a major victory for open source.

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