On Monday, the Supreme Court told Attorney General Eric Holder and President Obama that state police can indeed check the immigration status of people they stop--a big win for the Arizona Immigration law and for the rule of law throughout the country. It is also a setback to the President’s open border policy.

Three provisions of the Arizona immigration law were struck down, but the most important provision (Section 2B) was upheld. That provision requires Arizona police to make a reasonable attempt, when practicable, to determine a person’s immigration status during a “lawful stop, detention, or arrest” if there is a reasonable suspicion “that the person is an alien and is unlawfully present in the United States.”

The three parts struck down include, Section 3 which makes “willful failure to complete or carry an alien registration document” a state crime; #5C which makes it a misdemeanor for “a person who is unlawfully present in the United States and who is an unauthorized alien to knowingly apply for work, solicit work in a public place, or perform work as an employee or independent contractor in the state”; and #6 which authorizes state and local officers to make arrests without warrant where there is probable cause to believe “the person to be arrested has committed any public offense that makes the person removable from the United States.”

Five justices were in the majority, choosing to strike down the three provisions. Two dissenting justices—Antonin Scalia and Clarence Thomas—argued that the whole law should have been upheld, while a third dissenter, Justice Samuel Alito, would have upheld three provisions and struck down one.

In his decision with the majority opinion Justice Anthony Kennedy said, 

“The national government has significant power to regulate immigration. Arizona may have understandable frustrations with the problems caused by illegal immigration while that process continues, but the state may not pursue policies that undermined federal law.”

In his dissent Justice Scalia argued:

“If securing its territory in this fashion is not within the power of Arizona, we should cease referring to it as a sovereign stat.e”