Answer: The Supreme Court decides the definition of things. Its only unconstitutional if the Supreme Court says so.
That's how the USA can get away with... I dunno... the Office of Censorship in 1941. (https://en.wikipedia.org/wiki/Office_of_Censorship). Definitions change, not only due to different members on the Supreme Court, but also due to different circumstances (WW2 meant that the Supreme Court was willing to ignore the obvious incursion into the 1st Amendment, at least temporarily)
Whose definition?
Answer: The Supreme Court decides the definition of things. Its only unconstitutional if the Supreme Court says so.
That's how the USA can get away with... I dunno... the Office of Censorship in 1941. (https://en.wikipedia.org/wiki/Office_of_Censorship). Definitions change, not only due to different members on the Supreme Court, but also due to different circumstances (WW2 meant that the Supreme Court was willing to ignore the obvious incursion into the 1st Amendment, at least temporarily)
EDIT: I always forget that it was actually the Office of War Information that did the Hollywood Censorship thing (https://en.wikipedia.org/wiki/United_States_Office_of_War_In...), rather than the Office of Censorship.