No Supreme Court ruling today on Arizona's SB 1070

The U.S. Supreme Court did not rule today on SB 1070, Arizona's controversial anti-illegal immigration law that, among other things, would empower local police to check for immigration status.

The justices issued opinions today on four cases, but not on the most highly anticipated ones, which include SB 1070 and the Affordable Care Act. More opinions are expected Monday.

Oral arguments for Arizona v. United States were heard in April. The justices have been weighing whether four provisions of the state law are in conflict with federal immigration law, as the Obama administration asserted in its legal challenge filed in July 2010, shortly before SB 1070 partly took effect. That month, a federal judge in Phoenix issued a ruling temporarily blocking four of the measure’s most controversial sections.

The most contentious of these is Section 2(B), which allows state and local police officers to attempt to determine the immigration status of detainees if “reasonable suspicion” exists that they are in the United States without permission.

The lower court's decision was upheld by a federal appeals court. Arizona countered by petitioning the Supreme Court, which agreed to take the case late last year.

There's much riding on the Supreme Court's decision, which will have broad implications for states in terms of whether or not they can create and enforce their own immigration laws. Whichever way the court rules, the most immediate effect would be on states that have recently enacted anti-illegal immigration laws similar to SB 1070, among them Georgia, Alabama, South Carolina, Utah and Indiana.

There have been legal challenges to these state laws as well: Alabama, South Carolina and Utah have also been sued by the federal government on preemption grounds; others have been sued by civil rights groups. In some cases, court decisions are pending the Supreme Court's opinion.

More broadly, the ruling could either encourage more state immigration laws, or put the brakes on a trend that since 2010 has led numerous other states to at least consider their own immigration crackdowns.

One thing the high court isn't weighing in this particular case is the much-discussed civil rights aspect of SB 1070. Critics have pointed to the "reasonable suspicion" provision of the law as potentially encouraging racial profiling, and this has been part of other legal challenges. However, in this case, the justices are only weighing whether the contested provisions of the Arizona law are preempted by federal law.