The BSD License Grant

Here is the actual BSD license grant:

Redistribution and use in source and binary forms, with or without modification, are permitted provided.... ( BSD license.)

I will describe the provided... clause (what is also called a proviso ) soon, but first I need to describe just which of the University of California's intellectual property rights were actually being licensed by the first BSD license.

Almost everyone believes that the redistribution and use clause of the BSD license was intended to include all of the exclusive intellectual property rights the University then owned for something called the "Berkeley Software Distribution." The fact that the BSD license does not expressly list those exclusive rights (e.g., copy, create derivative works, distribute, perform, display, make, use, sell, offer for sale, import) doesn't mean they intended any of those rights to be excluded from the license.

The term redistribution means distribution again . This necessarily includes the right to make copies, since one cannot distribute software again without making copies. And since the word modification later in the sentence implies derivative work , I assume that the license allows the copying and distribution of both the original and derivative works. The word redistribution in the BSD license appears to encompass all those copyright rights that must be granted to ensure software freedom. The BSD license passes the filter of the Open Source Principles.

The word use , on the other hand, is not found among the exclusive rights of copyright owners . The use of software can be affected by a patent , because under the law, a patent owner has the exclusive right to make, use, and sell any product in which the patent is embodied. But the University of California made no patent grant in the BSD license. Indeed, later in the license the University specifically used the phrase this software is provided by the copyright holders and contributors , suggesting by its absence that there are no patent holders or that those patent holders are not granting anything in this license.

In the absence of an explicit patent grant, but considering the word use in the license, can we assume that the BSD license impliedly grants enough of whatever patent rights the University of California then owned that a licensee may use the software as it was originally distributed by the University? Most licensees under the BSD assume it does on the theory that otherwise the copyright license would be of no value. What good, they say, is software that can be copied but not used?

Such a conclusion is not based on the law of licenses. Indeed, a bare license of copyright need not include a bare license of patent at all. It is only if the BSD is viewed as a contract that we can introduce contract law principles such as reliance or reasonable expectations of the parties . If software is licensed under the BSD without forming a contract between licensor and licensee, the extent of any patent grant is at best ambiguous.

As to whether an implied grant of patent rights extends to versions of the software with modifications , that's an even more complicated question. The BSD license is silent about a patent license for derivative works. So if a licensee improves the original Berkeley Software Distribution in a way that infringes a patent owned by the University of California, there is no easy way of knowing whether an implied BSD patent license includes a patent license for that improvement.

Since courts are likely to construe implied grants of license narrowly, a licensee should consider obtaining separately from the licensor an explicit grant of patent rights that might be needed for modified versions of BSD-licensed software.