In his fervent defense Wednesday of Arizona’s right to crack down on illegal immigration, Justice Antonin Scalia likened immigration enforcement to crackdowns on bank robbers.

“What’s wrong about the states enforcing federal law?” Scalia said during his aggressive questioning of U.S. Solicitor General Donald Verrilli. “There is a federal law against robbing federal banks. Can it be made a state crime to rob those banks? I think it is.”

The Reagan-appointed justice mocked the Obama administration’s argument that S.B. 1070 unconstitutionally forces the federal government to re-prioritize its enforcement resources and go after undocumented people who are not dangerous.

“But does the attorney general come in and say, you know, we might really only want to go after the professional bank robbers?” Scalia said. “If it’s just an amateur bank robber, you know, we’re going to let it go. And the state’s interfering with our whole scheme here because it’s prosecuting all these bank robbers.”