The latest print edition of Which?, a prominent consumer group, has raised fresh concerns about the fallibility of evidence against "suspected" illegal file sharers that is being provided to UK broadband ISPs via organisations like ACS:Law solicitors. So much doubt has been cast that even the UK's Internet Service Providers Association ( ISPA ) has now raised its concerns.

ACS:Law is known to be targeting several thousand UK individuals with settlement requests (to avoid court action) of nearly £700, though Which? points to a sample of 20 cases that could be catching innocents. The situation is similar to that faced by lawyers Davenport Lyons last year, which found themselves being reported to the Solicitors Regulatory Authority (SRA) for "excessive" and "bullying" conduct (original news).

The magazine article suggests that ACS:Law has effectively picked up where the controversial Davenport Lyons left off and appears to be making some of the same mistakes, prompting the ISPA to say that even they are "not confident in [ACS:Law's] ability to identify [ILLEGAL] users". Typically such organisations track abuse by monitoring the Internet Protocol (IP) number/address of online users, which is assigned to your computer each time you go online.

Much as we've said before, IP addresses alone are not an effective way of determining a computer user’s true identity. They can easily be faked, hijacked, redirected and generally abused and used in ways that the systems employed by such trackers cannot detect. The only real way to be sure is to inspect a person’s hard disk.

For the ISP this presents a dilemma because while it may be possible to tell whether somebody was downloading from a P2P service on any given time and date, it is another matter entirely to identify the content of that download; doing so would require more aggressive monitoring (Deep Packet Inspection) and turn ISPs into police. It’s also incredibly easy to encrypt a P2P download.

The situation is such that if you happen to be downloading a legitimate update from a BitTorrent source, such as the latest World of Warcraft (WoW) patch, at the same time as somebody is hijacking your IP for an illegal one then it could be very difficult to prove your innocence.