[2] Funded by the Home Office, the IPCC operated under statutory powers and duties defined in the Police Reform Act 2002.

From April 2006, the IPCC took on responsibility for similar, serious complaints against HM Revenue and Customs and the Serious Organised Crime Agency in England and Wales.

It was a Non-Departmental Public Body (NDPB), funded by the Home Office, but by law entirely independent of the police, interest groups and political parties and whose decisions on cases are free from government involvement.

[5] Between 1 April 2004 and 31 March 2009 the IPCC used its powers to begin 353 independent and 759 managed investigations into the most serious complaints against the police.

There were a number of types of incidents that the police, or other agencies the IPCC oversees complaints for, must mandatorily refer to the commission.

[9] The IPCC's last chief executive was Lesley Longstone, who was responsible for running the organisation which supports the work of the commission.

They recorded the details of the complaint and made an assessment of the case and recommend a method of investigation, which would then be passed to a Commissioner for sign off.

Each commissioner also had responsibility for a particular portfolio such as firearms, deaths in custody, road policing and youth engagement.

[citation needed] Commissioners in making decisions on individual cases acted under the delegated authority of the commission.

[13] In February 2008 over a hundred lawyers who specialise in handling police complaints resigned from its advisory body, citing various criticisms of the IPCC including a pattern of favouritism towards the police, indifference and rudeness towards complainants, and complaints being rejected in spite of apparently powerful evidence in their support.

[14] The IPCC responded to these criticisms with a letter to The Guardian[4] in which the then IPCC Chair, Nick Hardwick, acknowledged some cases could have been handled differently in its infancy, but pointed out that despite repeated requests for the group to provide contemporary examples where expectations had not been met, there had been no further cases identified.

[16] However, the jury in criminal proceedings acquitted the police officer accused of manslaughter in the Tomlinson case.

The report was published on 29 January 2013[18] and was scathing,[19] describing it as "woefully underequipped and hamstrung in achieving its original objectives.