The Recording Industry Association of America (RIAA) has been hit by a legal mistake that could see it paying out substantial legal fees. 

The recording industry lobby group initiated action in November 2004 against Oklahoma housewife Debbie Foster, alleging that her IP address had been used to download music illegally.

Foster denied the claims but admitted that her husband and daughter also had access to the computer.

The RIAA then filed suit against Foster's daughter Amanda, and won the case since Amanda failed to defend herself.

The filing included Debbie Foster as the RIAA felt that she was still liable for secondary copyright infringement as she owned the account.

Foster responded by filing a claim of her own for "declaratory judgement of noninfringement".

A year and a half after filing the original claim the RIAA dropped its case, but Foster refused to drop hers.

Judge Lee R. West found that Foster was liable to sue the RIAA for attorney's fees, thought to be around $50,000, because she had not encouraged or even known about the fraud.

"The Copyright Act does not expressly render anyone liable for infringement committed by another. Rather, the doctrine of secondary liability emerged from common law principles," wrote Judge West.

"Under those common law principles, one infringes a copyright contributorily by intentionally inducing or encouraging a direct infringement."

Since there was no evidence of Debbie Foster encouraging the use of peer-to-peer downloads, the judge found that she had no case to answer and was free to recoup her costs.