Remember when Obama passed the law that allows for indefinite detention without charge? And how his supporters said "Yeah, but it's not like he would use it"?

Remember when Obama passed the law that allows for indefinite detention without charge? And how his supporters said "Yeah, but it's not like he would use it"? I think it's already used all the time across the country now. A law that "is not supposed to be used" should not exist. If it exists, then it will be used. I'm sure this is some kind of Murphy law or something.