He's a justice on the Supreme Court of the United States. And legally, he is correct. Punishment is what you get when convicted of a crime. If a policeman just sees you walking down the street and beats you up, or even brings you into custody and hits you to get information, he's not "punishing" you because no one has judged you as having done anything warranting punishment. Americans are protected from that sort of thing by laws against assault and torture, but not necessarily by constitutional restrictions on "punishment".
The Canadian Charter of Rights uses the words "cruel and unusual treatment or punishment", learning from 200 years of U.S. Constitutional law that you really have to spell out what you mean.
