Supreme Court rules cell phones cannot be searched without a warrant (2014)
msnbc.com
msnbc.com
"Riley v. California, 573 U.S. __ (2014), is a landmark[1] United States Supreme Court case in which the Court unanimously held that the warrantless search and seizure of digital contents of a cell phone during an arrest is unconstitutional."
I also doubt that this applies to cases where TSA asks travelers to unlock their phone.
[0] https://www.eff.org/wp/digital-privacy-us-border-2017#interi...