I think it's worth mentioning that software copyright licenses (like BSD) cover a particular implementation (a.k.a. "creative work") while U.S. patent licenses

I think it's worth mentioning that software copyright licenses (like BSD) cover a particular implementation (a.k.a. "creative work") while U.S. patent licenses cover a design. The likely reason for Facebook including the explicit patent license is that with an implicit license it is unclear if derivative works also share the rights to the granted patents (e.g. "can I take part of the implementation that utilizes a patented design and use it in another project?") [1]. The implicit patent rights of the BSD license may or may not extend to derivative works or different distributors, but the Facebook PATENTS file clarifies that it does not and avoids the ambiguity. For places outside of the U.S., that do not care about U.S. patent law, but do respect copyright, the BSD license is still in effect. I don't think that simply using Facebook software will open up your business to a "huge business risk" -- any more so than you'd be doing by working on the assumption of an implied patent right grant on the derivative works permitted by the BSD license. IANAL. [1] From the same thread: https://news.ycombinator.com/item?id=9113515 https://news.ycombinator.com/item?id=9113515