The decision in the case, which began in 2006, doesn't mean the site will shut down right away. The record labels and LimeWire are to meet with Judge Kimba Wood on June 1 to determine the next steps, such as a possible deal to work together going forward and a potential award for damages.
Recording Industry Association of America Chairman Mitch Bainwol said in a statement Wednesday that the ruling was "an extraordinary victory" against one of the largest remaining file-sharing services in the United States.
The RIAA said more than 200 million copies of LimeWire's file-sharing software have been downloaded so far, including 340,000 in the last week alone.
The ruling could pave the way for a deal, similar to the way Napster was sued out of existence in 2000 but was reborn and is now under the ownership of Best Buy Inc. with licensing deals with all the major recording companies.