The Importance of Mind Reading Machines

I don't think that we live in a world where it is unreasonable to expect that at some point, we really will be able to build essentially mind reading machines. And then I think like, boy, the American legal system has a really interesting question there. Of how much power do we grant to authorities? Where do we set the boundaries of personal liberty? "We also don't ban the police from then fingerprinting those tools or checking the bloodstones"