The Supreme Court's ruling boils down to this: Police get to assume you don't want your Constitutional rights. The Miranda warning -- the one you've heard cops say on TV a million times -- is now essentially meaningless.
"Today's decision turns Miranda upside down," Justice Sotomayor wrote in her dissent. "Suspects will be legally presumed to have waived their rights even if they have given no clear expression of their intent to do so."
Imagine if the government treated our other Constitutional protections this way. Federal agents would be free to shut down church services unless prayer was preceded by a pastor's public statement that churchgoers were exercising their First Amendment rights. Newspapers and bloggers would have to print the First Amendment on their front page to stave off a crackdown against criticizing the president. Gun owners would have to sign documents affirming their Second Amendment rights, or the government would be free to seize their firearms.
Sounds ridiculous, even un-American, right? So why should the Fifth Amendment right against self-incrimination be treated differently? Why should the government get to assume that you don't want your rights? Yes, there is a public interest in investigating and prosecuting crimes. But the Founders knew that interest could be abused, which is why they limited the government's police powers in the Constitution. Police don't like that, of course, but they're not supposed to. They're supposed to obey the rules anyway.
Constitutional rights are something that all American citizens are supposed to have. We're not supposed to have to jump through hoops in order to keep them; the government is supposed to jump through hoops in order to take them away. The Supreme Court, ironically led by "small government" conservatives, has now ruled otherwise. The Tea Partiers who routinely decry government tyranny might want to take notice.