""I'm not sure it is, and I'd argue the situation is unclear." I wouldn't. What you've quoted is Larry Rosen's view. Larry is a wonderful guy, but his views a

""I'm not sure it is, and I'd argue the situation is unclear." I wouldn't. What you've quoted is Larry Rosen's view. Larry is a wonderful guy, but his views are pretty far outside the norm for open source lawyers. To start "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." This is now settled since he wrote this. It is in fact a contract, that, if breached, leaves the licensor without a copyright license (causing both infringement of copyright and breach of contract). So you don't have to worry about this. The latter is a real issue, but one that most explicit grants don't solve either. In particular, apache/et al have explicit grants do not cover modifications by others that suddenly encompass patents. So you aren't any better off there either :)