The good news is that, at least in the U.S., a warrant (not a subpoena, that’s for civil matters) needs to be issued by a judge and can issue only if probable cause is provided. That’s a much higher standard than a border search, where no such limitations apply.

The law is a post-facto thing which you can use to sue if you want to lose some years of your life. It never actually helps prevent a bad situation. And to make it worse you’ll probably effectively be banned from traveling for being a troublemaker.