OMAHA -- A Kansas attorney filed a lawsuit Monday challenging the validity of a 2006 Nebraska law that allows some illegal immigrants to pay in-state college tuition.

Kris Kobach filed the lawsuit in Jefferson County District Court on behalf of six Nebraska residents. The lawsuit names the University of Nebraska Board of Regents and other state college boards as defendants.

The state law allows students whose parents brought them to the U.S. illegally to pay in-state tuition fees, as long as they have graduated from Nebraska high schools, lived in the state for at least three years and are pursuing or promise to pursue legal status.

In-state tuition is sometimes significantly cheaper than fees for out-of-state residents.

The Nebraska law was passed in 2005 over Gov. Dave Heineman's veto.

Nebraska is one of 10 states that allow illegal immigrants who meet certain criteria to pay in-state tuition rates for college. At least four -- Georgia, Oklahoma, Colorado, Arizona -- generally prohibit illegal immigrants from paying in-state tuition rates.

"This lawsuit not only saves Nebraska taxpayers money, it also vindicates Governor Heineman," said Kobach, who has fought similar measures in other states.

Kobach argues that Nebraska's law violates a 1996 federal law that prohibits higher education institutions from giving benefits to illegal immigrants without offering the same break to U.S. citizens.

Kobach, of Piper, Kan., is a former chairman of the Kansas Republican Party and a University of Missouri-Kansas City law professor known as a conservative spokesman, particularly on immigration issues. Kobach is currently running for the Kansas secretary of state seat.

His attempt to challenge Kansas' in-state immigration tuition law in federal court fell flat when the court determined that the plaintiffs -- a group of students paying higher out-of-state tuition -- hadn't proven they were harmed by the law.

In the Nebraska case, Kobach argues that residents' taxes are being used to support the state's immigration tuition law in violation of federal law.

Kobach led a similar lawsuit in California, which is pending before the California Supreme Court. A lower California court had dismissed the lawsuit, but a state appeals court reinstated the lawsuit in 2008, saying California law conflicted with federal law and the U.S. Constitution.

"In some portions, the California law and the Nebraska law are word-for-word identical," Kobach said.

University of Nebraska officials declined to comment on the lawsuit Monday.