Everyone will find something to quibble with in today’s highly technical ruling in Arizona v. United States, which is not an indication of some baby-splitting grand compromise but rather that this is a really complex area of law.  The Court, in an opinion by Justice Kennedy and joined by four other justices including Chief Justice Roberts, upheld (at least against facial challenge) Section 2(B) of Arizona’s SB 1070, which requires law enforcement officers to inquire into the immigration status of those they’ve lawfully detained if they have reasonable suspicion that the person is in the country illegally.  The Court found, however, that federal law trumped (“preempted”) three other provisions: Section 3, which makes it a state crime to violate federal alien registration laws (because Congress so comprehensively “occupied the field” of alien registration); Section 5(C), which makes it a state crime for an illegal immigrant to “knowingly apply for work, solicit work in a public place or perform work as an employee or independent contractor” (because it conflicts with the method of enforcement chosen by Congress – regulating employers rather than employees); and Section 6, which allows law enforcement officers to arrest someone they have probable cause to believe has committed a deportable offense (because questions of removability are entrusted to federal discretion).  Justices Scalia and Thomas wrote partial dissents to say they would’ve upheld the entire law.  Justice Alito also wrote separately to say he would’ve only found Section 3 preempted.

My own view most closely aligns with Judge Alito’s—I would uphold three of the four provisions, though for me 5(C) is the problematic one—but more important than the legal weeds are the two policy guides the Supreme Court has given:

1. The federal government has significant, near-exclusive powers to regulate immigration and even state laws that merely “mirror” federal immigration laws are on shaky legal ground;*
2. Although federal lawmaking trumps state lawmaking, federal policymaking does not.  Prosecutorial discretion, resource allocation decisions, and other policy processes do not preempt duly enacted state law.

In short, immigration policy by either state action or executive whim won’t cut it. The federal government—Congress and the president, working out that grand compromise—needs to fix our broken immigration system.

* Note that most of SB 1070 has been in effect since July 2010.  The federal government only challenged six of its provisions, and two (regarding transporting/harboring illegal aliens) were upheld by the district court, without further appeal by the government.  In other words, state laws dealing purely with state prerogatives (such as crime or business regulation) are on much firmer legal ground.