ACS:Law was a law firm based in the United Kingdom and best known for its actions taken against alleged copyright infringers using peer-to-peer file sharing.
The firm first started claims against copyright infringement in May 2009 and in November 2009 plans were announced to initiate claims against 25,000 individuals. In January 2010 it sent out 10,000 letters requesting payments of debt.
Following the dispatch of these letters in January over 150 people contacted Which?, a UK based product testing organization that also campaigns on consumer rights and protection issues saying they had been falsely accused.
This led to the start on an investigation by Which? Into ACS:Law's method of identifying suspectes by the IP address of the Internet user's connection using anti-piracy technology by Logistep. It was found that this technology can often result in a false positives. A study by ISP TalkTalk showed that innocent users can be accused of illegal activities carried out by a third party due to easy access to unsecured wi-fi networks.
By July 2010 the 418 official complaints had been made by the public to the Solicitors Regulation Authority about the conduct of ACS:Law and an investigation was launched and a Solicitors Disciplinary Tribunal set up.
The Tribunal is expected to deliver a judgement by the end of 2011. This is the third tribunal that has been set up to investigate the actions of Andrew Crossley, the firms only registered solicitor and main partner. In 2002 and 2006 he had been found guilty of conduct unbefitting a solicitor.
ACS:Law is also under investigation from the Information Commissioner for breach of the Data Protection Act due to the names and addresses of people accused by the firm being made visible on their website after the site came back online after a DDoS attack.
In January 2011, Andrew Crossley announced that the firm would cease to pursue illegal fileshares and the following month the firm ceased trading.