The debate over whether torture "worked" is beside the point.
The law doesn't say that torture is a crime unless it produces useful intelligence, any more than it says that murder is a crime unless it is profitable. It simply says that torture is a crime, always and in any circumstances. As it should.
Don't hold your breath waiting for the American legal system to punish the government officials responsible for the U.S. torture program. The greatest civil rights triumphs of the twentieth century were accomplished by principled activism to raise public consciousness about injustices.