intentions sometimes count

Jacob Sullum observes:

As I read the relevant Supreme Court decisions, if the [New York] police said they would randomly search bags [on the subway] for drugs, unlicensed guns or other contraband, mentioning in passing they would, of course, arrest anyone they happened to find with a bomb, the searches would be unconstitutional. But since they’ve said they are randomly searching bags for bombs, mentioning in passing they will also arrest anyone found with drugs, an unlicensed gun or other contraband, the searches probably will be upheld.