The U.S. Supreme Court has struck down three key provisions of Arizona’s tough immigration law but upheld one of its most controversial sections, which requires police to check the legal status of anyone they detain whom they suspect is in the United States unlawfully.

In the court's opinion, handed down on June 25, the three provisions were invalidated on a 5-3 vote and the fourth provision was upheld unanimously.

Arizona companies in construction and other industries now will be watching how the state begins to implement the parts of the law left standing.

The statute, known as S.B. 1070, was enacted in 2010 but has been blocked from taking effect by lower-court rulings.

Although the law has not yet been in force, Richard Usher, director of government relations for the American Subcontractors Association’s Arizona chapter, says the measure has had an impact on construction companies in the state.

Usher says some construction employers have had challenges in finding workers. And sources have said some Hispanic workers—including U.S. citizens who may have relatives here unlawfully—have already left Arizona because of fears of being detained or deported.

Just as the decision was split, so were reactions to it; supporters and opponents of the state law both found points in the court opinion to applaud and criticize.

The ruling is a partial victory for the Obama administration, which contended that four provisions of the 2010 Arizona law should be pre-empted by federal immigration policy.

The court agreed with the administration on three provisions. They would: make it a state crime—not just a federal crime—to be in the U.S. illegally; allow police officers to make a warrantless arrest of anyone they suspect is an illegal alien; and make it a misdemeanor for undocumented workers to seek employment in Arizona.

But some of the statute’s supporters viewed the ruling as a victory for states’ rights. Arizona Gov. Jan Brewer [R], who signed the bill in 2010, said, “After more than two years of legal challenges, the heart of SB 1070 can now be implemented in accordance with the U.S. Constitution.”