When a so-called McMansion threatens to cast its shadow on an undersized neighborhood, the fight that follows is usually about aesthetics and economics.

But in a neighborhood dispute in Montgomery County, it has become a battle over lawn signs and First Amendment rights to free expression.

It was bad enough, Nancy McCloskey said, when Montgomery officials approved plans for a six-bedroom, five-bathroom, 5,000-square-foot house on Overbrook Road in Brookdale, a Chevy Chase area neighborhood where most homes are about half to two-thirds that size.

Now, the agency that permitted the house has ordered McCloskey and other neighbors to remove lawn signs they planted in opposition to Thomas R. Eldridge's plans for his lot.

"It just makes me mad," McCloskey said. "The same people who allow this oversized house in our neighborhood tell me I can't put up signs in protest."

The dispute has attracted the attention of the American Civil Liberties Union, which has written to the county that the sign ordinance is unconstitutional.

At the center of the dispute is Eldridge, a former county prosecutor and unsuccessful candidate for Montgomery County Circuit Court judge in 2002. He lives in Somerset, where he serves on the Town Council, and plans to sell the Brookdale house as soon as it is finished, his builder said. Brookdale residents said they are determined to stop him because if he succeeds, others will inevitably follow.

"When you get one McMansion in a neighborhood and the developers get wind of it, the vultures come in," said Nancy Wolfe, one of about two dozen residents who during the summer put up lawn signs that said, "Council Member Tom Eldridge, We Don't Want Your McMansion for Profit in Our Neighborhood!"

Early this month, the county Department of Permitting Services, which in July approved Eldridge's plans for building the house, said the signs had to go. It cited a county law limiting lawn signs to no more than 30 days in a year, unless the resident wants to pay a $29.70 fee and apply for a permit.

When six residents refused a zoning inspector's order to remove the signs after 30 days, they were issued a violation notice, the first step toward fines that could approach $500 a day.

The ACLU, citing numerous Supreme Court decisions, wrote to County Attorney Charles W. Thompson Jr. that the order is unconstitutional because it restricts a person's right to express opinions on his own property.

"You only got 30 days of free speech in Montgomery County," said Richard Griffiths, an ACLU attorney.

Thompson didn't immediately dispute the ACLU's claim.

"The ACLU does a terrific job in the work they do, and they sent us a very thoughtful and researched letter, and we are looking into it," Thompson said.

The battle over the signs is part of a larger struggle playing out across the region as neighbors clash over big new houses that some say are out of scale with those around them.

In Brookdale, a neighborhood of narrow streets and mostly two-story houses near River Road and Western Avenue, the fight has gone from political to personal to legal.

Earlier this year, a limited-liability corporation headed by Eldridge bought a 2,000-square-foot house on Overbrook Drive for $630,00. Despite community opposition, the corporation received a permit in July to raze the house and replace it with one much larger.

"The house itself had a lot of problems," Eldridge said. "I think in close-in development, replacing older houses that have outlived their useful life is sound public policy."

Residents don't dispute that the house -- which had served as a rental unit for decades -- needed to be renovated or replaced.

But they say they never envisioned someone replacing it with one so big, even if it is allowed under the county zoning code.

The old house took up 10 percent of the lot's roughly 6,500 square feet, but the "footprint" of the new house will be about 35 percent.

And although most homes in the neighborhood are 21/2 stories, the plans for the new house appear to call for four, counting an attic and a first level that includes a garage and a bedroom. The house also would have a family room, dining room, living room, foyer, library, kitchen and breakfast area.

Residents say the house will be 40 feet at its highest point, although that depends on where it is measured from. The builder, Donald. T. Gibbons, said the house will be 30 feet, according to his calculations, well within the county's 35-foot limit in many residential zones.

"Is it bigger than the house that was there before? Yes," Gibbons said. "But then again, most condominiums are bigger than the house that was on the lot before we took it down."

Gibbons and Eldridge, who works on Capitol Hill, said they made several concessions to the neighbors, including shrinking the attic.

Neighbors, however, have been persistent in trying to try to stop the project, even though they agree that it complies with the law.

In July, they tried to deliver a petition to Eldridge pleading with him to reduce the size. Residents say he refused to accept it.

When the old house was torn down Aug. 1, residents gathered hundreds of signatures on a petition calling for the County Council to approve a moratorium on tear-downs. Last month, the Town of Chevy Chase approved a six-month freeze on the demolition and construction of houses to address residents' angst over mansionization.

Although there is no indication the County Council is willing to go that far, members are considering a proposal to restrict residential building heights to 30 feet.

Julie Schoo, with dog Max, is at a lot in Brookdale where a 2,000-square-foot house was razed to make way for a 5,000-square-foot house. Some residents who are upset about plans for the larger house have posted signs in protest.

This protest sign is posted at River and Brookdale roads in Montgomery County. The county has told residents that time is up for their signs.