Supreme Court justices, in a long-overdue slap at political correctness, have issued a ruling based so much on common sense and the First Amendment that one wonders why they had to get involved in the first place.

First Amendment guarantees of freedom of speech are virtually bulletproof, the courts have ruled for many years. Except in very, very rare cases, Americans are free to say and write whatever they desire, no matter how much someone else may dislike the comments.

But a 71-year-old law on trademarks allowed the government to refuse to register trademarks if someone in Washington decided terms used were offensive.

In 2011, an Asian-American rock band called The Slants attempted to trademark its name. The U.S. Patent and Trademark Office refused to register the name because it was disparaging toward Asians.

A more well-known case, still in a lower court, involves government refusal to register as a trademark the name of the Washington Redskins football team. That name offends native Americans, the bureaucrats ruled.

Fortunately, justices see the peril of such restrictions. They were unanimous in ruling against the government in The Slants case.

As the justices recognized, the First Amendment is too critical to be watered down because someone is offended — especially when government decides whether offense has occurred. Down that road can be found totalitarian regimes that muzzle critics because what they say is deemed offensive.

Why it took Supreme Court justices to understand that is more than a little unsettling.