PHILADELPHIA, July 12  -- A local real estate agent who describes herself as being in the top one per cent of all agents nationwide, has been named in a Federal lawsuit that accuses her of patent infringement by using a computer mapping system without acquiring a license to use the enabling technology.

The civil lawsuit against Diane Sarkisian of Ambler, Pennsylvania is the first of its kind. The suit naming Sarkisian was filed Tuesday in Federal District Court in Philadelphia. Lawyers for the patent owner, Real Estate Alliance, Ltd. (REAL), specifically noted that real estate agents throughout the country may be infringing the patent and subject to legal action.

The U.S. Patent (No. 5,032,989), "Real Estate Search and Location System and Method," was granted by the U.S. Patent and Trademark Office in 1991, at a time when the commercial use of the Internet was in its infancy. It covers a mapping system "for locating available real estate properties for sale, lease or rental using a database of available properties at a central location and remote stations which use a graphic interface," according to the document. The patent also includes a "drilldown" feature, under which specific areas can be displayed in greater detail.

Real estate agents throughout the United States, like Sarkisian, use this method as a valuable tool to locate desirable residential properties every day as they work with their clients. (The National Association of Realtors claims more than 1.11 million members.) The lawsuit states Sarkisian has not obtained a license to use the underlying technology, and asks for unspecified royalties plus court costs.

"The government has granted a patent, which is the right to enforce our intellectual property ownership," said Andrew Rooke, president of Real Estate Alliance, Ltd. (REAL), the patent's owner. "We intend to pursue those who are profiting by using our patented invention without a license. We have long been committed to mapping as a superior method for locating properties. REAL is gratified that systems vendors and multiple listing services who make mapping systems available to real estate professionals have come to the same conclusion. REAL is just seeking the royalties to which we are rightfully entitled."

As an example of REAL's commitment, the company states that it will not sue TReND, the local multiple listing service, for patent infringement. Rooke noted that prior to filing the lawsuit, REAL's lawyers contacted Sarkisian, offering her a full license for a fraction of what she is believed to earn annually from her use of the patented method. He further said that, according to his company's calculations, an average residential real estate agent may owe royalties of as much as $50,000 before the company's patent expires in 2008.

Lawyers for REAL said other real estate agents have been notified about their infringement of the company's patent as part of an ongoing process, and said additional civil lawsuits will be filed against agents across the United States who do not voluntarily obtain licenses