In a nationally watched case about a church's freedom to build where it pleases, the U.S. Justice Department has invoked a five-year-old federal law to investigate the way a New Jersey township has treated a 5,000-member church.

The probe of Rockaway Township's treatment of Christ Church is one of 25 such investigations the Justice Department has mounted in the last four years as religious organizations clash with local governments over zoning.

Of those, according to Justice Department spokesman Eric Holland, there have been five instances when the Civil Rights Division decided there was no basis for taking things further. Twelve investigations, Holland said, have resulted in "favorable settlements."

In three cases, the Justice Department went the additional step of filing civil rights lawsuits.

Justice Department involvement in a land-use case can make a town "wake up," said Derek Gaubatz, director of litigation for the Washington-based Becket Fund, a law firm that represents houses of worship in religious discrimination cases.

"It gives them the view of an objective outsider," Gaubatz said. "Zoning officials are used to running their fiefdoms and having the final say, exercising discretionary criteria in a discretionary way that hurts religious houses of worship."

But others, including Rockaway Township Mayor Louis Sceusi, view Justice Department involvement differently.

"I believe they are infringing upon a local government's ability to govern its own growth," he said. "Clearly they do not have a firsthand knowledge of the area that they're dealing with. I do believe it's an issue of states' rights."

Rockaway Township was notified by letter in September that the federal government was investigating the township's handling of Christ Church's plans to build there. The 5,000-member Montclair church has been before the township planning board for a year and a half seeking site plan approval. The church wants to build a complex that would include a sanctuary for more than 2,500 people, a K-5 school and other amenities.

The church's plans have come under fire from some in town who cite concerns about the plan's scope and environmental impact. The church, in the meantime, has filed a federal lawsuit alleging that the township has put up "discriminatory and improper barriers" to the church's religious mission.

Both the church's lawsuit and the Justice Department's investigation invoke the Religious Land Use and Institutionalized Persons Act, a federal law that protects churches from governments' making zoning decisions that restrict religious freedom.

The law was signed by President Bill Clinton in September 2000 after it unanimously passed both houses of Congress. Most of its enforcement has come during the Bush administration. Three years ago, the Department of Justice even created a special position to oversee religious discrimination issues.

Detractors of the law point out that the man appointed as the Justice Department's special counsel for religious discrimination, Eric Treene, used to work for the Becket Fund.

"In my experience, the Becket Fund is never far from any of these investigations," said Marci Hamilton, an attorney who specializes in land-use religious discrimination cases and is the author of "God vs. the Gavel: Religion and the Rule of Law."

Gaubatz denied having asked the Justice Department for an investigation of Rockaway Township. Christ Church officials also have said they did not ask for the investigation.

"We don't really know who instigated this investigation, but we certainly welcome it," said Marc Weinstein, a Christ Church spokesman.

Holland, the Justice Department spokesman, said, "DOJ officials first heard about [the Christ Church application] through the news."

Holland said religious-land-use probes have spanned the religious spectrum.

He said the Justice Department has gone as far as filing lawsuits in Florida, where the city of Hollywood ordered a halt to Orthodox Jewish services being conducted in two homes; in Rockland County, N.Y., where the department alleges that the village of Airmont's zoning code discriminated against a Hasidic Jewish boarding school; and in Hawaii, where the Hale O Kaula Church needed a special permit to build on agricultural property. In that case, the county's insurance company settled the case with a $700,000 payment to the church.

The county of Maui was in settlement negotiations when the Justice Department filed suit, said Madelyn D'Enbeau, one of the Maui deputy corporation counsels who handled the case.

The main effect of the Justice Department's intervention, D'Enbeau said, was expense. D'Enbeau also raised questions about the transparency of the process. After the case ended, she said, the county asked the Department of Justice to explain why it came after the county but never got an answer.

"If they really truly felt that Maui County . . . didn't protect religious rights, we want to know what it is that you think we're doing wrong," she said.

Christ Church in Montclair, N.J., says in a lawsuit that Rockaway Township is foiling its plan to build a new sanctuary.