As should be evident from the previous discussion, drafting a new open source license is probably not the best place to start for most open source projects. In addition to the extra time and expense associated with drafting any legal document, the use of a new license will discourage potential contributors from participating in the project. Those contributors who are concerned about licensing implications will want to read and understand the license. Particularly in the case of long or complex licenses, this may present a substantial barrier to entry.
If you choose to do it, however, the first step in drafting an open source license should be retaining a competent and experienced attorney to undertake the task. While many open source licenses have been drafted by non-lawyers, the drafting of any contract, particularly one with the complexities inherent in open source software licenses, should be undertaken by someone with professional knowledge and experience.
After securing counsel, the next step should probably be devising the basic mechanics of the license. The new author should give serious thought to what the function of the license is intended to be. With open source and free software licenses, the key issue will generally be the generational limitations placed on distribution and modification of the licensed work by licensees. Many of the possible limitations have already been described. The MIT and the BSD Licenses, for example, require only that the text of the license be included in the subsequent distribution and that the required attributions be made. The GPL imposes much more substantial limitations: any distribution or modification of the work by licensees must be consistent with the terms of the GPL. If a licensee wishes to modify and distribute the work, he or she must license future users of that modified work under the GPL. The MPL imposes somewhat similar restrictions for modifications to the licensed work, but it permits either the original or the modified work to be distributed as part of a "Larger Work" under another license, including a proprietary license.
The number of potential variations is nearly infinite. The Open Source Definition, described in Chapter 1, imposes some specific requirements for a license that the author wants to have certified as compliant by the Open Source Initiative.
A brief summary of those requirements follows here. An open source license must permit an open development model to be applied to the licensed work, in that the source code must be provided or otherwise made available with the executable version of the code. The license must permit free modification of the licensed work and free distribution of both the original and the modified work. The license cannot discriminate in its application against any person or group of persons or any field of endeavor.
Of course, a license need not be compliant with the Open Source Definition to be an effective license. But if the intent is to draft an "open source license," failure to comply with the Open Source Definition is a pretty good sign that the drafter is not headed in the right direction. Beyond the fundamentals of the Open Source Definition, there is considerable scope for creativity and ingenuity in drafting licenses.
Many of the licenses described in this book, such as the Apache License, v2.0, and the MPL, begin with long, comprehensive lists of definitions. While not necessary, using such definitions can avoid unnecessary repetition of the same language throughout the license. A definitions section can also avoid accidental, and apparently inconsequential, variations in phrases or sentences that are supposed to be identical. Such variations can lead to potentially serious problems in interpreting the license, as users and contributors, and possibly lawyers, judges, and juries, attempt to determine whether the use of slightly different language was accidental or intentional.
Disclaimer of warranties and limitation of liabilities clauses are virtually universal in open source licenses. While certainly not required by the Open Source Definition, they are prudently included in such licenses to protect the licensor and any potential contributors from liability. Such clauses are not unique to open source licenses many commercial software licenses contain similar terms.
The use of choice of forum and choice of law clauses is relatively uncommon in open source licenses, but there are many situations in which such clauses could be advantageous to the licensor, particularly for "developer-centric" licenses, such as the Apache License, v2.0, and the Perl License. With such licenses, it is anticipated that the project will remain primarily under the control of its initial developer. That developer may want to choose a local forum and the application of local law for the convenience of the developer in the event any dispute arises under the terms of the license. For example, a developer located in Boston may want to identify the Massachusetts state courts located in Boston as the forum for any dispute under the license and for Massachusetts law to control the interpretation and enforcement of the license. When considering the use of such clauses, developers should consult with a lawyer to make sure that the law that they are choosing to govern the license will interpret and enforce the license consistent with the developer's understanding. Laws vary significantly among different locales: it is certainly possible that a New York court would reach a different conclusion than a Massachusetts court as to how a contract should be interpreted.
One final area that a developer should give some thought to addressing is the applicability of patents to the licensed work. In order to prevent patent litigation to the extent possible, it is probably worthwhile to include a clause in the license that grants specific permission for users to exercise a royalty-free right to any patents held by the licensor, and, depending on the terms of the license, any subsequent contributors.
For a list of licenses that the Open Source Initiative has approved as conforming to their expectations of open source, and for information about their process for approving licenses, visit http://opensource.org/licenses/.