The American music industry says it is not targeting small-time internet song-swappers but is going after those downloading "substantial" amounts of music.
There are fears about the methods used by the RIAA
The Recording Industry Association of America (RIAA) was replying to concerns from senator Norm Coleman over what he calls an "excessive" campaign.
The RIAA plans to file several hundred lawsuits against people suspected of illegally sharing songs on the internet.
Mr Coleman, chairman of the Senate Governmental Affairs' Permanent Sub Committee on Investigations, is planning to hold hearings on the campaign.
But RIAA president Cary Sherman said the industry group was not going after occasional downloaders.
"RIAA is gathering evidence and preparing lawsuits only against individual computer users who are illegally distributing a substantial amount of copyrighted music," said Mr Sherman in a statement.
Mr Sherman added the trade group "does not condone any illegal copying and does not want anyone to think that even a little illegal activity is acceptable".
Mr Coleman, who worked as a rock roadie in the 1960s, fears the punishment for the illegal downloading of songs is too heavy for the crime.
Copyright laws allow damages of between $750 (£473) and $150,000 (£95,000) per song.
Last year a number of US students were fined between $12,500 (£7,890) and $17,000 (£10,730) each after being sued by the RIAA.
Although it has yet to file the new lawsuits, the RIAA has given assurances they will be dealt with in a "fair and equitable manner".
Pressure group NetCoalition, which represents hundreds of internet service providers, is concerned about the methods the RIAA is employing to track those using the internet to download music.
It has called on the RIAA to reveal how it reaches its decisions on who should be subpoenaed.