As part of a lengthy letter to Senator Lindsay Graham, the P2P United trade association said on Wednesday that file-swapping companies should not be held to a standard that is technologically infeasible.
Lawmakers "have been deliberately misinformed by self-interested industry about the technological capability of peer-to-peer services," said Adam Eisgrau, P2P United's executive director. "It is not that we won't filter out copyrighted material and inappropriate sexual material. It's that we can't."
The group's claim, backed up by considerable technical documentation, comes as calls for filtering of file-swapping networks are rising in Congress and in courts.
Graham and a quartet of other legislators sent a letter to P2P United's member companies last November, asking for assurances that the file-swapping companies would attempt to stop illegal material from being traded through their networks.
Most pointedly, the letter asked that the companies work to create some kind of filters that could block copyrighted material and pornography.
File-swapping companies have contended that this kind of filter is impossible in a decentralised system such as Gnutella or Kazaa.
In older file-swapping services such as the original Napster, in which searches were routed through a central point, a filtering mechanism was more feasible.
But in wholly decentralised networks, in which searches radiate out through a constantly shifting array of "nodes," or individual computers, filters are impractical, the group said. Only by forcing the networks to change into something else -- a centralised system, for example -- would effective filters be useful, the group added.
However, some companies say they have the ability to do some effective filtering.
A company called Audible Magic, which installs song-recognition software inside Internet service provider networks, with the promise of identifying and blocking trades of copyrighted songs, demonstrated its software to members of Congress and the press in Washington D.C.
The demonstrations, set up by the Recording Industry Association of America (RIAA), were intended to refute the notion that filtering is impossible on file-swapping networks.
"Audible Magic proves [filtering] can be done," RIAA chief executive officer Mitch Bainwol said. "This is not speculation; it's a real live technology that's on the market today. If the peer-to-peer community is serious about becoming legitimate, one would think they would explore this kind of technological tool to help address the piracy problem."
P2P United's Eisgrau said that neither the RIAA nor Audible Magic had contacted the organisation or its members with any information about the technology. He said that the file-swapping members would be happy to do a live engineering test under the auspices of Congress.
"If the equivalent of cold fusion has been invented in the software context, it ought to be a matter of science and engineering to see if it works," Eisgrau said.
The two sides may be talking about different types of filters, however.
As currently offered, Audible Magic's technology functions inside telecommunications or corporate networks, essentially serving as the equivalent of a roadblock, looking into cars -- or in this case, data packets -- as they pass and obstructing unauthorised information. That could stop file swappers on a given service provider's network, but would do little to impede swapping overall.
By contrast, a filter that worked universally throughout a distributed file-swapping network such as Kazaa would probably have to be integrated into the software itself. Additionally, unless a gigantic and constantly changing database of songs, movies and other material were to be included along with every piece of file-swapping software, it would require the software filters to check in with a central server each time a trade or search was initiated.
Peer-to-peer companies say they don't intend to add those centralisation features to their software and note that a federal judge has said that decentralised file-swapping network tools such as Gnutella are legal to distribute. An appeals court will re-examine that ruling next week.
