WHEN PRESIDENT Donald Trump signed an executive order on April 24th authorising seabed mining for critical minerals, he meant to free American companies from international constraints and license their roving hands to search for precious stones on the bottom of the deepest oceans—Earth’s last mining frontier. The order was a bombshell. Though America has never ratified the UN Convention on the Law of the Sea (UNCLOS), under which the regulation of seabed mining sits, it had long accepted its provisions as customary international law. And the International Seabed Authority (ISA), created under UNCLOS, currently forbids mining.