The "fire in a crowded theater" line is by Justice Oliver Wendell Holmes, Jr. in Schenck v United States.[1] During the first World War, he ruled that it was constitutional to send socialists to prison for distributing leaflets that protested the draft.

The judicial precedent set in that case was overturned in Brandenburg v Ohio.[2]

1. https://en.wikipedia.org/wiki/Schenck_v._United_States

2. https://en.wikipedia.org/wiki/Brandenburg_v._Ohio