Which law allows the death penalty for allegedly transporting drugs?

Shooting first and asking questions later is how we got into this mess of deporting us citizens.

Sections 105 and 108 of the United Nations Convention on the Law of the Sea allows any country to go after drug smugglers in international waters but it does require that a court in that country approve of the action. It's certainly worth questioning if a court can issue a preemptive ruling on a proposed action against alleged drug smugglers. There's also the issue that Maritime Law is weird, convoluted, and probably sanctions most state actions if you dig around enough.