Privateers. State sanctioned pirates who area permitted to prey on pirates. Kill they and take thir stuff.
Offer a bounty too.
If nations are legally powerless to stop pirates, are they legally powerless to stop people I might pay to kill pirates?
Hmmm...Q-ships. I like it.
To declare war, grant letters of marque and reprisal, and make rules concerning captures on land and water;
A privateer was a private warship authorized by a country's government by letters of marque to attack foreign shipping.
The U.S. Constitution authorizes Congress to issue letters of marque. But this Congress wouldn’t have the guts to even think about it.