The MPL and Patents

The MPL also deals with patents much more thoroughly than any preceding open source license.

To review, a patent is a grant under power of law of the right to exclude others from making, using, selling, offering to sell, or importing certain specifically claimed inventions . The claims in a patent can be licensed to others. The MPL actually defines Patent Claims more precisely as "including, without limitation, method, process, and apparatus claims in any patent Licensable by grantor." (MPL section 1.10.1.) This is consistent with the types of utility patents actually granted by the U.S. Patent and Trademark Office. Fortunately, these technical distinctions among types of claims won't be important for us here.

First, the Initial Developer grants a patent license:

...Under Patents Claims infringed by the making, using or selling of Original Code, to make, have made, use, practice, sell, and offer for sale, and/or otherwise dispose of the Original Code (or portions thereof). ( MPL section 2.1[b].)

Notwithstanding Section 2.1(b) above, no patent license is granted: 1) for code that You delete from the Original Code; 2) separate from the Original Code; or 3) for infringements caused by: i) the modification of the Original Code or ii) the combination of the Original Code with other software or devices. ( MPL section 2.1[d].)

These complex provisions draw important lines around patented intellectual property. They are the first explicit patent grant we've yet seen in open source licenses. The licenses I described earlier in this book contain at most implied patent grants. (If a license, like the GPL, is a bare license , then there may be no implied patent grant at all.) Implied patent grants are, at best, ambiguous.

Under the express provisions of the MPL, an Initial Developer licenses his or her patent claims to licensees of a specific embodiment of software, the Original Code , without limiting the Initial Developer's right to exclude others from making, using, or selling other embodiments in other software.

Patent Claims are potentially valuable even if the Initial Developer doesn't realize initially how his or her inventions will later be applied. The developer may discover that his or her claims cover very different applications from what was originally conceived, or such claims may cover applications that combine technology contributed (or kept proprietary) by others. Thus, Patent Claims infringed by the making, using or selling of Original Code may find applications broader than just making, using, or selling the Original Code.

For example, a patent claim for a cut/paste function licensed under the MPL for use in specific Original Code that does word processing ("WP version 1") may have other valuable applications, such as in an email or graphics program. Consider an open source licensor, an Initial Developer, who distributes WP version 1. That licensor owns a patent that contains three valuable claims, which I will paraphrase very incompletely (and unprofessionally, were I actually writing patent claims) as follows :

1. Software to perform a cut/paste function.

2. The software of claim 1 for a word processor.

3. The software of claim 1 for an email program.

The Initial Developer (i.e., the patent owner and MPL licensor) grants enough patent rights so licensees can make, use, or sell WP version 1, the Original Code . (See MPL section 2.1[b].) Licensees under the MPL thus obtain limited licenses to the Initial Developer's broad claim 1 and the narrower claim 2. (Claim 1 is broader than claim 2 because claim 2 only applies to word processors, but claim 1 applies to any cut/paste application.)

• Does the MPL patent license allow licensees to create and distribute a derivative word processor, WP version 2, which includes a cut/paste function? Probably not. The MPL patent license covers the Original Code only, or portions thereof . (MPL section 2.1[b].) We'd have to examine WP version 2 to make sure that it contains at least the portions of Original Code that perform the cut/paste functions. If the cut/paste software in the Original Code is modified, the Initial Developer 's patent license doesn't cover it. (MPL section 2.1[d].)

• Can a licensee perform cut/paste functions in different word processors obtained from other licensors? Not if that software infringes the original licensor's broad claim 1 or narrower claim 2. The MPL patent license doesn't cover software separate from the Original Code . (MPL section 2.1[d].)

• Can a licensee perform cut/paste functions in email programs? No. The MPL patent license excludes claims that aren't infringed by making, using, or selling the Original Code . (MPL section 2.1[b].) The Initial Developer 's narrow claim 3 is excluded under the MPL license because an email claim is not infringed by the original word processing program.

• Can a licensee perform cut/paste functions in graphics programs? Not without a separate license to the Initial Developer 's broad claim 1. Notice that, in this example, the Initial Developer doesn't have a claim specifically covering graphics programs, but the cut/paste claim 1 is broad enough to apply to such new applications. Suppose that a Contributor invents a new graphics application for Initial Developer 's claim 1. Nothing prevents anyone from patenting separately an improvement on someone else's patent claim; he or she simply can't practice his or her improvement without a license to the broader claim. Two companies might thus create patent claims worth cross-licensing with each other, one a broad claim covering cut/paste, and the other a narrower claim covering cut/paste in graphics programs. Note that neither patent owner is required by the MPL to license his or her patent claims (the Initial Developer's claim 1 or the Contributor' s graphics claim) to each other for open source or proprietary graphics programs.

In other words, the original MPL patent license applies only to claims 1 and 2, and only to a specific Original Work and to certain types of authorized Modifications .

As for a Contributor , this is that subsequent licensor's reciprocal patent license:

...Under Patent Claims infringed by the making, using, or selling of Modifications made by that Contributor either alone and/or in combination with its Contributor Version (or portions of such combination), to make, use, sell, offer for sale, have made, and/or otherwise dispose of: 1) Modifications made by that Contributor (or portions thereof); and 2) the combination of Modifications made by that Contributor with its Contributor Version (or portions of such combination). ( MPL section 2.2[b].)

Notwithstanding Section 2.2(b) above, no patent license is granted: 1) for any code that Contributor has deleted from the Contributor Version; 2) separate from the Contributor Version; 3) for infringements caused by: i) third party modifications of Contributor Version or ii) the combination of Modifications made by that Contributor with other software (except as part of the Contributor Version) or other devices; or 4) under Patent Claims infringed by Covered Code in the absence of Modifications made by that Contributor. ( MPL section 2.2[d].)

"Contributor Version" means the combination of the Original Code, prior Modifications used by a Contributor, and the Modifications made by that particular Contributor. ( MPL section 1.2.)

These provisions deal with Modifications submitted by Contributors who are licensees of the Original Work . Each Contributor grants a reciprocal license for his or her own patents to allow Modifications to be made, used, or sold either alone or in combination with the Original Work . So if a Contributor invents cut/paste software that works for graphics, or an entirely different invention (such as a new way of processing fonts), and includes it in his or her Contribution , that claim is reciprocally licensed to the Initial Developer, to all other Contributors , and to all subsequent licensees , under terms similar to the complex ones I've just described.

Furthermore, these provisions don't mean that the Contributor can automatically obtain a license to the Initial Developer 's claim 3 simply by creating a Modification that adds an email function; the Initial Developer , who has the right to license that patent claim, has specifically excluded it. (See MPL section 2.1[d].)

If you intend to become a Contributor , you may need an additional patent license from the Initial Developer or an earlier Contributor before you can make, use, or sell your Modification .

The MPL makes this explicit but, under the patent laws, the same issue exists under all the open source licenses, with their potential implied patent license grants, previously discussed in this book. Anyone planning to create improvements to open source software must obtain licenses to any patent claims necessary to make, use, or sell those improvements. A patent grant from the licensor that would cover improvements is not implicit or explicit in any of the licenses I've discussed so far.

I like to think of such implied or explicit patent license restrictions as field of use restrictions; they limit the patent, sometimes in subtle ways, to use in specific fields or applications. How should we deal with field of use restrictions in open source licenses, where the copyright license provides unlimited freedom for licensees to create derivative works but the patent license does not?

The Free Software Guidelines, the Open Source Definition, and the Open Source Principles from Chapter 1 provide no guidance. They do not mention patents at all. The fundamental activities that open source deals with are copying, modification, and distribution. That's copyright law. What about patent rights: making, using, selling and offering for sale, and importing?

I believe the following is the only answer consistent with open source principles and with existing open source licenses:

An open source license must grant enough patent rights to allow the licensee to make, use, sell, offer for sale, or import the open source work as distributed by its licensor. Any additional license rights for derivative works or other uses are at the option of the licensor.

The first sentence , identifying the minimum scope of a patent grant in an open source license, probably describes how a court would decide anyway in the absence of an express patent grant in the license ”at least for a contract although not for a bare license ”because a right to copy software is usually meaningless without a right to make and use, and the right to distribute is meaningless without the right to sell.

The second sentence describes an option for increasing the scope of the patent grant and so doesn't belong in a mandatory Open Source Principle.

I ultimately decided to leave this patent principle out of the Open Source Principles entirely because several important already-approved open source licenses don't say anything at all about the scope of the patent grant. Otherwise we might have to declare some existing open source licenses incompatible with this patent principle, further confusing people about what open source really means.