Why 'I have nothing to hide' is legal consent to a search

Stop me if you've heard this one. Officer asks if he can look in your trunk. You say, 'I don't have anything to hide.' [pause] That's not an explanation. That's consent. I had a client — trunk search, nothing illegal in it, but the stop turned into forty minutes on the side of the highway and a missed job interview. He told me afterward he just didn't want to seem suspicious. [pause] Here's what he didn't know. The Fourth Amendment gave him the right to say no. No justification required. Just: 'I don't consent to searches.' That's the whole sentence. Instead he said seven words that handed over that right entirely. And once you've consented, courts have upheld those searches consistently. Walking it back is nearly impossible. [pause] You are allowed to be innocent and still say no. Those are not in conflict. [chuckles] The officer cannot punish you for knowing your rights. If he asks again, you say it again. 'I don't consent to searches.' You had the right. One sentence gave it away.