[Southack]

Article I, Section 8
"Clause 11: To declare War, grant Letters of Marque and Reprisal, and make Rules concerning Captures on Land and Water; "

Notice that Congress is given full authority by our Constitution to make its own laws concerning all captures on land and water.

HINT: That's precisely what Congress did when it ratified the Geneva Conventions.

[inquest]

Notice that Congress is given full authority by our Constitution to make its own laws concerning all captures on land and water.

And that does not entail the power to authorize what the Constitution does not allow.