A federal judge blocked police in Arizona from enforcing a section of the state's 2010 immigration enforcement law that prohibited people from blocking traffic when they seek or offer day labor services on streets.

U.S. District Judge Susan Bolton ruled Wednesday that groups seeking to overturn the law will likely prevail in their claim that the day labor rules violate the First Amendment. She rejected arguments by the state that the rules were needed for traffic safety and pointed out that the law, also known as SB1070, says its purpose is to make attrition through enforcement the immigration policy of state and local government agencies.

"This purposes clause applies to all sections of SB1070, and nowhere does it state that a purpose of the statutes and statutory revisions is to enhance traffic safety," the judge wrote.

The ban was among a handful of provisions in the law that were allowed to take effect after a July 2010 decision by Bolton halted enforcement of other, more controversial elements of the law. The previously blocked portions include a requirement that police, while enforcing other laws, question people's immigration status if officers suspect they are in the country illegally.

The U.S. Supreme Court has agreed to hear Gov. Jan Brewer's appeal of Bolton's decision to put the most contentious elements of the law on hold. Another appeals court has already upheld Bolton's July 2010 ruling.