A. Amendment 1
Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press, or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
From your post:
'"Freedom of expression" is not unlimited.'
Which one of us misread this?
The USSC has ruled that the Freedom of Speech does not extend to yelling "MOVIE!" in a crowded firehouse.
(Actually, it does, but there are consequences. Even "words like conviction can turn in to a sentence")