I recall reading fiction in which there was a big difference between a privateer and a pirate. Privateers were 'licensed' pirates, given a letter of marque that

I recall reading fiction in which there was a big difference between a privateer and a pirate. Privateers were 'licensed' pirates, given a letter of marque that allows them to attack enemies of the state. The point being that, plundering french ships under an English letter of Marque will prevent the french from calling you a pirate. Instead, you are simply an enemy combatant. I think this was from a Wilbur Smith novel.