"It did not take long for Justice Antonin Scalia to side with Arizona [regarding SB 1070], and it was not much later that Chief Justice John G. Roberts, Jr., showed that he, too, was inclined that way. Justice Clarence Thomas, who said nothing during the argument, is known to be totally opposed to the kind of technical legal challenge that the government has mounted against S.B. 1070. That left Justices Anthony M. Kennedy and Samuel A. Alito, Jr., as the ones that might be thought most likely to help make a majority for Arizona." - Lyle Denniston, Apr. 25, 2012

See the Transcript of the Supreme Court Oral Argument in Arizona v. US  docs/supreme court.pdf