FBI cannot even look at your phone lock screen without a warrant, rules judge
Precedents are interesting:<p>> Bond v. United States, 529 U.S. 334, 337 (2000) (concluding Border Patrol agent searched a bag by squeezing it)<p>> Arizona v. Hicks, 480 U.S. 321, 324–25 (1987) (holding officer searched stereo equipment by moving it so that the officer could view concealed serial numbers).<p>The idea seems to be that pushing the power button is what constituted a search, not taking a picture of the lock screen. Presumably if the lock screen was somehow already on at that point (which normally it wouldn't be) then it might be fair game to take a picture without a warrant.