A war of words between the Montgomery County Association of Realtors and a Potomac software company has gone from the negotiating table to U.S. District Court in Baltimore, with each party suing the other and claiming unfair trade practices.

The realty trade group filed suit against Realty Photo Master Corp. of Potomac on Aug. 9, alleging that the company's computerized pictorial real estate listing systems violate the copyrights of association listing services and contractual forms.

This week, Realty Photo Master struck back, suing all 20 of the association's board members, the association's executive director and its lawyer and the Shannon & Luchs realty firm.

The countersuit claims that the board is trying to create a monopoly for Shannon & Luchs, the only area brokerage with an in-house computerized property listing system that shows would-be buyers pictures of houses for sale. Such a monopoly, the suit said, comes at the expense of smaller realty firms that rely on the Realty Photo Master system to show customers computerized pictures of houses on the market.

"We have examined the copyright issue extensively and have no doubt the case is completely without foundation," said Realty Photo Master attorney Lanny Davis. "They are using the lawsuit to deter {association} members from subscribing to our services."

George Ballman, the association's attorney, rejected those claims.

"That's one hundred percent erroneous," Ballman said. "The basis of our lawsuit is merely to protect the integrity of the {association's} multiple listing service, {which lists almost all houses for sale}. It has nothing to do with Shannon & Luchs or any other broker."

The road to the courtroom has been long and contentious for both sides. Industry officials said the barbed threats and insinuations that have accompanied each suit demonstrate increasing tension in the real estate market, which has suffered a slowdown in recent months.

"I'm not at all surprised that the two parties are trying to defend their turf," said Jim Peterson, a real estate consultant in Fairfax County. "Much of the barbs that are being thrown around go back to the age-old issue of the large broker versus the small broker."

The association first objected last spring to Realty Photo Master's service, which allows subscribers to gain access to the association's multiple listing service along with computerized pictures of each property.

In June, the company urged its subscribers and other small realty firms to submit petitions to the association protesting the trade group's stance against Realty Photo Master. One subscriber, Potomac broker Frederic Thomas, resigned from the association's board because of its continued opposition to Realty Photo Master.

Efforts to negotiate a settlement broke down early last month. The association filed suit amid a flurry of letters it and Realty Photo Master sent to real estate brokers in which each side proclaimed its innocence and accused its opponents of lying and cheating.

And this week's counterclaim did nothing to stem the barrage of insults. Defense counsel "has been threatening {to file suit} at the top of his lungs for some time," said Edward Colbert of Kenyon & Kenyon, co-counsel for the association. "Naming the individual members of the board is simply a make-weight attempt to get attention in the media."

The conflict threatens to divide the association's membership as the home-buying public becomes more familiar with the concept of pictorial listing services.

"The MLS system is a pillar of the community, and there is usually a consensus on it," said one Washington-area realty association executive. "I'm sure there will be a lot of people watching this case very closely."