When does the freedom of speech not apply?

Freedom of speech does not protect against treason, violation of national security, extreme obscenity, dangerous speech (such as shouting "fire" in a crowded place), or conspiracy. It also does not protect one who knowingly lies to harm another person (perjury, libel, slander). Freedom of speech does not allow anyone to disrupt lawful processes - for example shouting down a teacher or outbursts in a courtroom.