On May 26, 2011, the Supreme Court ruled, in a 5-3 decision, that the Legal Arizona Workers Act was not preempted by federal legislation.

The main questions presented in this case were the following: The Supreme Court had to determine whether the federal law that states companies cannot be punished for hiring undocumented workers unknowingly, except in cases of licensing, would prevent a state, such as Arizona, from having a law imposing sanctions on employers that hired undocumented workers.

In the majority opinion, Chief Justice Roberts accepted the arguments that the state of Arizona had made about how the initiative was narrow and closely tracked and was modeled after the objectives of the 1986 federal law.

[7] Justice Breyer, dissenting, had indicated during oral arguments that he believed that "Congress… had taken 'an absolutely balanced' approach" in an attempt to ensure undocumented workers were not able to get jobs but make sure as well that businesses did not discriminate in hiring to avoid the risk of losing its license.

In her dissent, Justice Sotomayor indicated that the majority had "turned states loose to determine for themselves whether someone has employed an unauthorized alien so long as they do so in conjunction with licensing sanctions.