The First Amendment has never covered all speech; bribery, threats, extortionate offers, misleading advertising, perjury and unlicensed medical advice are all unprotected. Indeed, in 1918, when Eugene Debs went to jail for sedition on account of speeches urging people to resist military service, the First Amendment wasn't even held to cover the type of political speech that is currently recognized as lying at its very core. So the argument cannot be that pornography is speech, so it must be protected. Instead, the argument must be made that it is the type of speech that ought to be protected by the First Amendment.

--The New Yorker