Editor's note: Edward Morrissey is a senior editor and correspondent for the conservative commentary website HotAir.com.
(CNN) -- One of the most anticipated Supreme Court decisions in recent times -- Obamacare -- was not announced Monday. That gave an air of anti-climax to an important decision that was handed down, one with its own political baggage and implications for the election, although not nearly as fraught with peril as the health care law.
In any other session, the outcome of Arizona v. United States might have been the headline case of a Supreme Court season. Instead, the Obama administration will have to celebrate an incomplete victory in the next 72 hours before the court delivers its ruling on the fate of Obama's signature legislation.
The White House largely won in challenging Arizona's harsh 2010 immigration law, although it might be difficult to sell that point. Last year, the 9th U.S. Circuit Court of Appeals struck down four provisions of the law, ruling that the federal government pre-empted state regulation on immigration. The Supreme Court mostly agreed.
Unfortunately for the administration, the Supreme Court reversed the lower court on the most controversial part of the law, the "show me your papers" provision that requires law enforcement officers to check the immigration status of people while enforcing other laws.
Arguably, this provision was designed to force the federal government to take action on illegal immigrants by identifying them to the Department of Homeland Security.
By upholding this provision, the Supreme Court allowed Gov. Jan Brewer to claim victory for Arizona's immigration enforcement efforts:
"Today's decision by the U.S. Supreme Court is a victory for the rule of law. It is also a victory for the 10th Amendment and all Americans who believe in the inherent right and responsibility of states to defend their citizens. After more than two years of legal challenges, the heart of SB 1070 can now be implemented in accordance with the U.S. Constitution."
But that narrow win is tenuous. The court pointedly did not rule that the provision was constitutional, which means that further court cases may well strike it down at a later date. Arizona can put it into effect, but it probably won't take too much time before a case comes up that will put the provision back under scrutiny.
The White House will portray the Supreme Court's ruling on immigration as a principled victory over a state that had infringed on federal prerogatives to manage immigration. It may even get a couple of days' worth of traction on that argument. That won't last long, though, for two reasons.
First, the coming Obamacare ruling will vastly overshadow this nuanced win by Thursday morning. Second, this win serves as a reminder that the Obama administration has done a poor job of enforcing immigration law -- and along with Obama's recent decision to stop deporting some young illegal immigrants -- border states have no reason to expect a second term that will improve on the first.
Follow us on Twitter @CNNOpinion.
Join us on Facebook/CNNOpinion.
The opinions expressed in this commentary are solely those of Edward Morrissey.