The pact would bar each country from investigating the other's citizens, and the US couldn't use data from UK companies in any case where the death penalty is an option.

Like other politicians, UK Home Secretary Priti Patel has claimed that end-to-end chat encryption helps terrorists, and that intelligence agencies should have backdoors to investigate suspicious activity. As always, though, there are a number of problems with this strategy. In addition to basic privacy concerns, there's not really such a thing as an authorities-only backdoor -- it's really introducing a vulnerability that anyone can use, including hostile countries and criminals. There's a chance measures like this could simply drive crooks to other services while punishing well-meaning users.