A new study from the University of Washington suggests that media industry trade groups are using flawed tactics in their investigations of users who violate copyrights on peer-to-peer file sharing networks.

Those trade groups, including the Motion Picture Association of America (M.P.A.A.) Entertainment Software Association (E.S.A.) and Recording Industry Association of America (R.I.A.A.), send universities and other network operators an increasing number of takedown notices each year, asserting that their intellectual property rights have been violated under the Digital Millennium Copyright Act.

Many universities pass those letters directly on to students without questioning the veracity of the allegations. The R.I.A.A. in particular follows up some of those notices by threatening legal action and forcing reported file-sharers into a financial settlement.

But the study, released Thursday by Tadayoshi Kohno, an assistant professor, Michael Piatek a graduate student, and Arvind Krishnamurthy, a research assistant professor, all at the University of Washington, argues that perhaps those takedown notices should be viewed more skeptically.

The paper finds that there is a serious flaw in how these trade groups finger reported file-sharers. It also suggests that some people might be getting improperly accused of sharing copyrighted content, and could even be purposely framed by other users.

In two separate studies in August 2007 and May of this year, the researchers set out to examine who was participating in BitTorrent file-sharing networks and what they were sharing. The researchers introduced software agents into these networks to monitor their traffic. Even though those software agents did not download any files, the researchers say they received more than 400 take-down requests accusing them of participating in the downloads.

The researchers concluded that enforcement agencies are looking only at I.P. addresses of participants on these peer-to-peer networks, and not what files are actually downloaded or uploaded — a more resource-intensive process that would nevertheless yield more conclusive information.

In their report, the researchers also demonstrate a way to manipulate I.P. addresses so that another user appears responsible for the file-sharing.

An inanimate object could also get the blame. The researchers rigged the software agents to implicate three laserjet printers, which were then accused in takedown letters by the M.P.A.A. of downloading copies of “Iron Man” and the latest Indiana Jones film.

“Because current enforcement techniques are weak, it is possible that anyone, regardless of sharing content or using BitTorrent, could get a D.M.C.A. takedown notice claiming they were committing copyright infringement,” said Mr. Piatek.

In their paper, the researchers argue for greater transparency and public review of Big Media’s intellectual property enforcement actions.

“Our study scientifically shows that flaws exists,” said Mr. Kohno, an assistant professor in the university’s Computer Science and Engineering department. “It’s impossible to prove that other flaws don’t exist, especially since current industry practices are so shrouded in mystery. Ultimately, we think that our results should provide a wake-up call for more openness on the parts of content enforcers.”