We've all heard of the doctrine of states rights, code word for slavery up to the time of the Civil War and not much good since. There are also rights forbidden to the state, appearing in Article I, Sec. 10. Clause (1) of that prohibits states from issuing letters of marque.
Letters of marque? What are those.
Perhaps you'd like to read one, here.
A letter of marque was a permit to go a-pirating against enemy shipping, in the days before there were navies of sufficient size and why not take advantage of the merchant fleet and the adventurous types who manned them. In the name of the king the old sea dogs could prey on such wonderful things as the Spanish treasure fleet.
When you had the permit in hand, the letter of marque, you fought, and profited, in the national interest and were a hero, a rich hero if you intercepted the treasure armada en route to Spain from the Americas. That's one reason the bottom of the Caribbean, the Spanish Main, is littered with bones and doubloons.
If you played the same game without the permit, you were a pirate. They had those too. Didn't have to split the rewards with the king.
Why were the states forbidden to issue letters of marque? They could get the U.S. in plenty of trouble internationally if they could, couldn't they.
Today we might store this under constitutional trivia. Or historical curiosity. But it's in the text, so we might as well know what we're talking about when we come across the archaic term.