A US judge has told the Recording Industry Association of America (RIAA) that it needs to present more evidence of illegal file-sharing if it wants to prosecute individuals.
However, US senior district court judge Rudi M Brewster said that the plaintiffs had not shown enough evidence to rule in their favour and referred to their case as "speculation".
"Plaintiff here must present at least some facts to show the plausibility of their allegations of copyright infringement against the defendant," said the judge.
"Other than the bare conclusory statement that on 'information and belief' defendant had downloaded, distributed and/or made available for distribution to the public copyrighted works, Plaintiffs have presented no facts that would indicate that this allegation is anything more than speculation."
The legal challenge was filed against Rodriguez on 14 November 2006, and a summons was served exactly one month later.
Rodriguez was accused of downloading copyrighted recordings and making them available for other internet users.
The record companies have 30 days from the judgement to amend the complaint and serve it again.
The RIAA has recently been countersued by an Oregon woman after the organisation withdrew a two-year legal case against her for alleged file sharing activity.
The trade body is also being pursued for legal costs by a mother accused of "secondary copyright infringement" because her IP address was used to download files.
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