A US woman whose lawsuit against the Recording Industry Association of America (RIAA) was thrown out by a federal judge last month plans to file an amended complaint in a move that could finally force the industry group to share details about its controversial techniques for investigating alleged file sharers.

The closely watched case involves Tanya Andersen, a disabled single mother who in June 2005 was accused by the RIAA of illegally downloading and distributing copyrighted music files. The case (Atlantic Recording v Andersen) was voluntary dropped by the RIAA in August 2007 amid a flurry of counter-claims by Andersen, who accused the organization of malicious prosecution, libel, negligence, invasion of privacy, electronic trespass and fraud.

After the lawsuit was dropped by the RIAA, Andersen was allowed by the court to drop her counter-claims and file them instead as a direct legal action against the RIAA. That lawsuit was filed in August 2007 and charged the RIAA and five music labels with a string of misdeeds. Andersen's lawsuit included charges that the recording labels had used unlicensed investigators to illegally gather evidence against her and that the RIAA had violated the US Racketeering Influenced and Corrupt Organizations (RICO) Act.

Andersen's suit was dismissed on February 19 by US District Court Judge Anna Brown. In her ruling, Brown said that Andersen had failed to adequately state her claims for relief and gave her until March 14 to file an amended complaint clearly identifying the legal basis for each of her claims. The judge also noted that the court would not permit any more motions to dismiss the case by the RIAA.

That means if Andersen's amended complaint passes muster, the RIAA will be forced, for the first time in its pursuit of illegal music sharers, to disclose its investigative technique, according to Lory Lybeck, the US-based attorney for Andersen.

"We are going to have discovery," Lybeck said. "That's important because [the RIAA] has spent three years actively refusing to provide any discovery of any significance in the growing number of cases," that it is pursuing, he said. "It is very important for them to operate in secrecy because once their methodology is revealed it will be obvious they committed a crime," he said.

According to Lybeck, the amended complaint will ask the RIAA to provide details on a variety of issues including how exactly Media Sentry goes about collecting its evidence against alleged copyright infringers, when the RIAA first engaged Media Sentry to carry out such investigations, and how it decides which file sharers to sue.