WIST

Your right to swing your arms ends just where the other man’s nose begins.

Oliver Wendell Holmes, Jr. (1841-1935) American jurist, Supreme Court Justice
(Spurious)


Usually attributed to Holmes (or Abraham Lincoln, or John Stuart Mill), but actually first raised in legal commentary by Zechariah Chafee, "Freedom of Speech in Wartime", 32 Harvard Law Review 932, 957 (Jun 1919):

Each side takes the position of the man who was arrested for swinging his arms and hitting another in the nose, and asked the judge if he did not have a right to swing his arms in a free country. “Your right to swing your arms ends just where the other man’s nose begins.”

There are earlier versions in non-legal contexts dating back decades earlier, often in arguments for Temperance and Prohibition. See here for more background.

Variants:

• "The right to swing my fist ends where the other man’s nose begins."
• "The right to swing my arms in any direction ends where your nose begins."
• "My right to swing my fist ends where your nose begins."