Updated at 8:15 p.m. ET
SALT LAKE CITY - The U.S. Justice Department filed a lawsuit Tuesday challenging Utah's immigration enforcement law, arguing that it usurps federal authority and could potentially lead to the harassment and detention of American citizens and authorized visitors.
"A patchwork of immigration laws is not the answer and will only create further problems in our immigration system," said Attorney General Eric Holder in a statement. "The federal government is the chief enforcer of immigration laws ... it is clearly unconstitutional for a state to set its own immigration policy."
The lawsuit was filed Tuesday in Salt Lake City's U.S. District Court after months of negotiations between Justice Department attorneys, state attorneys and elected leaders. Justice officials said they plan to continue those discussions despite the lawsuit.
Other federal agencies included in the lawsuit are Homeland Security and the State Department.
Even with the federal intervention, state officials remained confident the law would eventually be sustained.
"The Legislature worked diligently to craft a law that would pass constitutional muster," said Ally Isom, spokeswoman for Gov. Gary Herbert. "We hope the courts do the right thing."
The Utah law, signed by Herbert in March, requires people to prove their citizenship if they're arrested for serious crimes ranging from certain drug offenses to murder. It also gives police discretion to check citizenship on traffic infractions and other lesser offenses.
Although the Utah law was modeled on Arizona's strict enforcement measure that was passed in 2010, lawmakers worked to address some of the biggest concerns. Chief among those was the requirement that police check the immigration status of anyone they arrest and the ability for police to verify the status of anybody they legally encounter.
Civil rights groups filed a lawsuit earlier this year, and a federal judge granted a temporary restraining order in May against the law, House Bill 497. A hearing on that lawsuit is scheduled for Dec. 2.
But that hearing may be delayed because of the federal lawsuit, National Immigration Law Center general counsel Linton Joaquin said. The NILC, along with the American Civil Liberties Union, is handling the original lawsuit against the state.
The federal lawsuit "reinforced the claims we've been making all along," Joaquin said. "The Utah law is preempted by federal law and is unconstitutional."
Utah's enforcement law was part of an immigration reform package signed by Herbert this year. Among those was a program that will allow illegal immigrants with jobs to live and work in the state that federal officials also argue is unconstitutional, but they are holding off on a lawsuit because it doesn't go into effect until 2013.
Originally, federal officials told Utah Attorney General Mark Shurtleff that they planned to include the guest worker law in their lawsuit. He said the fact they only focused on the enforcement measure in this lawsuit demonstrates their willingness to work with the state.
"We're now adversaries in the courtroom but we're going to continue to discuss this with them," Shurtleff said.
Three other states that have passed strict enforcement laws in the past two years have been sued by the Justice Department, including Arizona, South Carolina and Alabama.
Arizona Gov. Jan Brewer has urged the U.S. Supreme Court to hear an appeal on an injunction against key parts of the state's law. Federal judges have also blocked parts of the South Carolina and Alabama laws.
The department is still reviewing laws passed earlier this year in Georgia and Indiana.