Solicitor General Donald Verrilli precipitously changed course at the Supreme Court last Wednesday, as the justices’ skepticism toward the Obama administration’s main argument against Arizona’s 2010 immigration law became painfully clear. Until last week, the administration had argued that SB 1070 was pre-empted by federal immigration authority. “Pre-emption” doctrine holds that a state law conflicts with federal law if it stands as an obstacle to some congressional purpose.