General international law got rid of privateering in 1856.
However, the US never signed that treaty, though it has not issued any letters of marque, I believe, since the War of 1812.
There is no legal reason we can’t authorize privateering, though our privateers would have problems since no other nations would recognize the legitimacy of their authorization to wage war.
It was proposed during both of the great wars, if my memory serves.
“There is no legal reason we can’t authorize privateering,”
This has my vote as one of the most thought provoking posts of the year.