WASHINGTON - Deep inside the national headquarters of the Recording Industry Assn. of America (RIAA) is a purple room.

Tinted windows shade the faces of young men and women working behind computer screens. They are part of the team investigating the illegal sharing of music files over peer-to-peer (P2P) networks, and they protect their identities carefully.

Such precautions are a reflection of the charged environment in which the music business is operating. The RIAA, the trade group for the major US labels, views anti-piracy enforcement as vital to the recording industry's future.

Since 2003, labels have filed more than 28,000 lawsuits against individual file sharers. Only one suit has reached trial. Jammie Thomas, a single mother who was ordered by a federal jury in Minnesota last October to pay $222,000, is waiting for the federal court's decision on her request for a new trial.