15,000 suspected filesharers in the UK could soon be getting a letter from a company called ACS:Law which accuses them of sharing copyrighted material illegally, offering the chance to settle out of court for "several hundreds of pounds".

The letters are due to be sent out in early 2010, and consist of accusations from two German clients: DigiProtect and MediaCat. Software is used to monitor networks and harvest IP addresses - law firms then demand that ISPs turn those IP addresses into real-life names and addresses, which then receive a nastygram in the post.

Andrew Crossley of ACS:Law told the BBC: "We give them the opportunity to enter into a compromise right at the start to avoid having to deal with it [in court]". Taking it to court would result in damages of "several thousands of pounds", Crossley claims.

But many are sceptical of the law firm's methods. Consumer group Which? says that it had messages from 150 people who claim to have been wrongly accused and that many were accused of downloading pornography. As a result, quite a large percentage pay up out of embarrassment, whether or not they're guilty.

ACS: Law are currently "under investigation" by the Solicitors Regulation Authority (SRA), but a spokesperson told the BBC that it could not divulge any more details about the nature of the complaints. The Law Society has also received complaints about the firm.

Have you received a letter like this in the past? Did you pay up, or fight it, and what happened? Let us know in the comments.