If it goes ahead, the action will be the largest crackdown on P2P users in Europe to date.
Landwell, the legal arm of PricewaterhouseCoopers, earlier this month issued the threat on behalf of clients that have remained unnamed to avoid a backlash by consumers. The company said it had gathered data such as IP addresses on 95,000 file-traders by tapping into P2P systems with older versions of the P2P clients, which don't encrypt such information.
Landwell said it is working with Spain's Technological Investigation Brigade (BIT) on the prosecutions and expects the case to appear in court next month. The action mimics a large-scale assault on alleged file-swappers in the United States by the Recording Industry Association of America (RIAA), which is in the process of filing several hundred lawsuits against them.
However, civil liberties and Internet user groups say they doubt whether the case is valid under Spanish law, or indeed whether it will even be filed, calling it a scare tactic to dampen the use of P2P systems.
Article 270 of the Spanish penal code specifically allows people to share files as long as there is no profit involved. Carlos Sanchez Almeida, a lawyer specializing in Internet issues, pointed out that this provision has led to several previous cases related to P2P networks and entertainment-related files being thrown out of court.
"To make (files) freely available to other users can constitute a civil liability, but never a crime, when it lacks...the spirit of profit," he wrote in an opinion published on Spanish civil rights Web site Kriptopolis.
Xavier Ribas, the principal Landwell lawyer on the case, asserted in a responding piece that while people might not be selling the files, "profit" could be defined as acquiring a copyrighted work for free. "In the case of works of entertainment, the utility or benefit can arise from the simple act of enjoyment of the work: to listen to a song or see a film without having to pay for it," he wrote.
European Digital Rights (EDRI), a coalition of European digital rights groups, said the case was insubstantial and would probably never be filed, noting that Ribas said in a recent radio interview that the lawsuit had not yet been presented to the court.
"Analyzing and comparing the arguments, it becomes quite clear that the lawsuit is nothing more than an attempt to create fear amongst Spanish users," EDRI's David Casacuberta said in a statement.
Spain's Association of Internet Users (Asociacion de Internautas) said Landwell was unlikely to be able to track down individual users based on the information they had acquired so far. "It is just their IP address, and it's up to a judge to issue an order to disclose the user identity and check if some illegal activity has been taking place", he said.
The Association of Internet Users has joined a storm of protest in Spain against the legal threats, offering the group's lawyers to anyone who is targeted by suits.
Legal proceedings against U.S. peer-to-peer users kicked off earlier this month when the RIAA sent out subpoenas to ISPs in preparation for filing hundreds of lawsuits against P2P users. Web traffic monitoring company Nielsen/NetRatings said that since June, illegal file-sharing activity in the United States has fallen by around 15 percent.
Neither Landwell nor PricewaterhouseCoopers returned requests for comment.
Matthew Broersma of ZDNet UK reported from London.