An Arizona judge says police can immediately start enforcing the “show me your papers” provision of the state’s controversial immigration law, marking another legal milestone in the two-year battle between Gov. Jan Brewer and the Obama administration over the handling of undocumented immigrants.

The ruling by U.S. District Judge Susan Bolton on Tuesday is the first legal go-ahead for Arizona law enforcement officers to question the immigration status of people suspected of being in the country illegally.

In June, a U.S. Supreme Court decision upheld the provision on the grounds that it doesn't conflict with federal law. This month, Bolton said she would not ignore the clear direction from the Supreme Court that the provision “cannot be challenged further on its face before the law takes effect.”

The Obama administration has argued that federal law trumps Arizona law. Civil rights activists argued that the provision would lead to systematic racial profiling and unreasonably long detentions of Latinos.

Tuesday’s decision is the judge’s follow-up move, directing officers to enforce the provision to see if it will be challenged in court by a person questioned by police under the provision.

Immigrants rights activists say the judge’s decision means that officers in Arizona may be making questionable traffic stops as early as this afternoon.

“The next step for us is to document the abuses and provide the evidence the court has said we need to provide,” Alessandra Soler, executive director of the American Civil Liberties Union in Phoenix, told the Los Angeles Times.

“We will do everything we can. We have a community hot line and community forums planned, and we are training people, trying to get the message out that people need to report abuses,” Soler said.

A coalition of civil rights groups is awaiting a ruling from the 9th Circuit Court of Appeals on its latest effort to prevent the questioning requirement from taking effect.

“The motivating factor of this law was discriminatory in its intent,” Linton Joaquin, a lawyer for the  National Immigration Law Center, told The Times. “It’s clear that this is unconstitutional.”

Arizona's law was passed in 2010 by voters frustrated that their state was the nation’s busiest illegal-entry point into the country. Brewer took the immigration measure to the Supreme Court after a federal appeals court struck it down.

Since then, five states — Alabama, Georgia, Indiana, South Carolina and Utah — have adopted variations on Arizona's law.

Even after Bolton’s ruling, many proponents of the “show me your papers” provision have questioned how the new legal framework will work in reality. They say that federal immigration agents, who will be called to verify people's immigration status and be responsible for picking up illegal immigrants from local officers, might try to stonewall the process.

Federal immigration officers say such cases will come after other priorities, such as catching repeat violators coming across the border and identifying and removing those who threaten public safety and national security.

In recent weeks, lawyers for Brewer had urged Bolton to put the provision into effect, saying opponents were bluffing in asserting that its enactment would lead to racial-profiling claims.