PHOENIX - A part of Arizona's 2010 immigration law aimed at day laborers and employers who hire them is unconstitutional and unenforceable, a federal appeals court ruled Monday.

The 9th U.S. Circuit Court of Appeals rejected the state's argument that it can make it a crime for someone looking for work to enter a car stopped on the street. That law also criminalizes drivers who stop to pick up laborers.

Attorneys for the state said Arizona has a legitimate interest in ensuring that traffic is not blocked.

But Appellate Judge Raymond Fisher, writing for the unanimous three-judge panel, said it would have been one thing if the state simply made it illegal to block traffic.

Instead, the provision of SB 1070 specifically - and only - targets day laborers. And that, Fisher said, makes it a unconstitutional infringement on the First Amendment rights of the individuals.

Fisher also said that lawmakers, in adopting the 2010 legislation, made it clear that they were less interested in traffic safety than in discouraging illegal immigration. He noted the measure spells out that one goal is to make life so difficult for people living here illegally that they leave the state.

And he said the penalty in SB 1070 is "far out of line" with punishments for other similar traffic violations.

Fisher said, for example, that the law already on the books in 2010 said someone who recklessly impedes traffic can be jailed for up to 30 days. But a day laborer who merely impedes traffic can end up behind bars for six months.

"The imposition of a much harsher penalty for those who block traffic while engaging in labor solicitation speech evidences the desire to suppress such speech," he wrote.

Rep. John Kavanagh, R-Fountain Hills, who wrote the original language, said Monday he wants to appeal to the U.S. Supreme Court.

"I still believe that the current law that deals with obstructing traffic doesn't deal with this type of activity and that we need a separate statute," he said.

But the last time the nation's high court reviewed provisions of SB 1070, it struck down three and upheld only the one that requires police to check the immigration status of those they have stopped when they have reason to believe the person is in this country illegally. And the justices said they would revisit that if there is evidence the law is being applied unfairly.

Fisher said U.S. District Judge Susan Bolton, who last year blocked the state from enforcing the provision, properly concluded that its purpose was to suppress labor-solicitation speech rather than to promote traffic safety.

Gov. Jan Brewer, who signed the law in 2010, said she had not seen the ruling.