[ceejayoz]

https://www.law.cornell.edu/uscode/text/17/107

> Notwithstanding the provisions of sections 106 and 106A, the fair use of a copyrighted work, including such use by reproduction in copies or phonorecords or by any other means specified by that section, for purposes such as criticism, comment, news reporting, teaching (including multiple copies for classroom use), scholarship, or research, is not an infringement of copyright.

(Emphasis mine.)

[falcolas]

Fair use is a positive defense though, so you'd have to go through a trial (assumption being Facebook throws enough lawyers at it to make it impossible for a "it's obviously fair use" argument work) to assert it.