Joshua Montano, left, and Deborah Robles protest in front of the state capitol the day after Arizona Gov. Jan Brewer, in an executive order, reaffirmed Arizona state law denying young illegal immigrants driver's licenses and other public benefits, Aug. 16, 2012, in Phoenix. (Ross D. Franklin/AP Photo)

It's taken more than two years, but a controversial provision of Arizona's strict immigration law called "show me your papers" is one big step closer today to going into effect.

The provision-which requires a police officer to ask someone he stops for his papers if the officer has a reasonable suspicion the person is in the country illegally-was a part of Arizona's strict immigration law that was signed by Gov. Jan Brewer on April 23, 2010.

The Obama administration challenged the law in the Supreme Court last spring arguing that it interfered with existing federal law.

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But Justice Anthony Kennedy, writing for the court, ruled against the administration on that provision of the law. Kennedy wrote, "There is a basic uncertainty about what the law means and how it will be enforced. At this stage, without the benefit of a definitive interpretation from the state courts, it would be inappropriate to assume [the provision] will be construed in a way that creates a conflict with federal law."

Immigration groups rushed back to district court, challenging the law on civil rights claims.

Yesterday United States District Court Judge Susan R. Bolton ruled against the groups. She is expected to issue an order allowing implementation within the next several days.

"It's a matter of real concern…because it will cause real problems with racial profiling and illegal detention," said Omar Jadwat an attorney at the immigrants' rights project at the ACLU. "The courts have made very clear that additional challenges are available once the law goes into effect and we are certainly going to pursue all of the options available to us."

Brewer praised the ruling: "As I have said consistently, it is not enough that this law be enforced. It must be enforced efficiently, effectively and in harmony with the Constitution and civil rights. I have no doubt Arizona's law enforcement officers are up for the task ahead."