SALT LAKE CITY -- Police in Utah have been given the authority to check the citizenship status of anyone they arrest -- even if only for a few hours.

The new law, House Bill 497, went into effect Tuesday, although civil rights attorneys spent much of Monday trying to persuade state officials to voluntarily delay its implementation.

U.S. District Judge Clark Waddoups has a hearing scheduled Tuesday afternoon in Salt Lake City where he could decide to halt enforcement of all or some of the law.

The crux of the argument against the regulation is that it is similar to an Arizona law that is already working its way through the courts.

The Utah law, signed by Republican Gov. Gary Herbert in March, requires people to prove their citizenship if they're arrested for serious crimes -- ranging from certain drug offenses to murder -- while giving police discretion to check citizenship after traffic infractions and other lesser offenses.

As long as the law can be enforced, the American Civil Liberties Union and National Immigration Law Center warn the fallout could include racial profiling and the unlawful detention of U.S. citizens. The two groups filed a lawsuit last week challenging the measure's constitutionality.

Police chiefs and county sheriffs, however, said very little will change in their handling of immigration laws, and none of them expected a rash of immigration-related arrests. No department contacted by The Associated Press reported any special training or preparation.

"We're not going to be knocking on doors or rounding up people in the parks," Washington County Sheriff Cory Pulsipher said. "The people we're coming in contact with are already engaged in other criminal behavior."

The citizenship status of anyone booked into a Utah jail for a felony or drunken driving is already checked because of a law passed in 2008.

The new law goes further, allowing officers to arrest people for minor offenses if they can't prove their legal presence in the country, which has frightened many Hispanics, Salt Lake City Police Chief Chris Burbank said.

Already, the department is hearing from shelters and rape crisis centers about victims who refuse to talk to the police because they fear deportation.

"We do our job based on community trust," Burbank said. "When a segment of the community doesn't trust us, the rest of the communities lose trust in the police."

Despite claims by opponents that the law it is almost identical to the Arizona law, Utah leaders closely scrutinized their version for constitutional red flags, said the bill's sponsor, Republican Rep. Stephen Sandstrom.

Law enforcement has mostly been supportive of the bill, as well.

"They're going to use this as a tool," Sandstrom said. "They were confident they could implement it, because it's spelled out pretty clearly when a person would be checked."

Two other immigration laws went into effect Tuesday as well.

One law would allow people to sponsor immigrants to the country if they accept financial liability, such as medical costs, housing and transportation. Although legislative attorneys raised constitutional concerns during the lawmaking session that ended March 10, no lawsuits have been filed to overturn that law.

Another law will allow Utah employers to hire temporary workers from a Mexican state, although an agreement between the two states was still being negotiated.

Another immigration law that won't go into effect until 2013 would create a program that allows illegal immigrants to remain in the state.

All four measures have been touted as part of the Utah Compact, which was backed by religious and business leaders as a way to balance enforcement provisions with economic realities. The Compact also emphasized the importance of keeping families together.

The Compact is being emulated in other states, including Georgia, Indiana and Maine.

Critics argue the Compact is pushing amnesty laws, especially with the guest worker program.