The mother of murdered teenager Stephen Lawrence said sections of Britain's communities were fully aware that the "police do tell lies" long before the so-called "plebgate" scandal.
Speaking in the week that she took her seat in the House of Lords, Baroness Lawrence of Clarendon said she had personal experience of officers not telling the truth.
In an interview with The Independent she said: "People like me know the police do tell lies." She added: "It is not all police officers but there are elements within the police force that do tell lies."
Earlier this week the Independent Police Complaints Commission suggested police officers should face misconduct hearings over allegedly misleading accounts of a conversation with Tory MP Andrew Mitchell. He was forced to resign as Chief Whip after it was claimed he had called Downing Street officers "plebs".
The row escalated after Prime Minister David Cameron said he was convinced there had been "wrongdoing" and described the conduct of officers as "unacceptable". Mr Mitchell was also backed by the Home Secretary Theresa May who suggested he should receive an apology. An internal investigation by West Mercia police into the affair concluded they had no case to answer.
Baroness Lawrence said her family had first-hand experience of police duplicity in their long battle for justice for the teenager who was murdered in 1993.
"What happened around Stephen's case was when we were going around the private prosecution we were told by the officers that after going back over the papers they could not believe how bad the original investigation was.
"Then when we had the inquest one officer under oath said the first investigation went fine and the only problem was with the family liaison officer when they had specifically said to us how bad it was. Why lie at that point? They wanted to make us look bad and to appear as if we were the ones that caused all the problems. Police officers do lie," she said.
Baroness Lawrence said she intends to use her position as a Labour peer to provide a "voice for the ordinary people". She said more needed to be done to help combat soaring unemployment rates amongst young black men particularly in London and that there should be a review of sentencing guidelines to reduce the disproportionate number of black people sent to jail.
Two leading barristers are due to report in December on claims made by a former undercover officer that the Metropolitan Police conducted a smear campaign against the Lawrence family and their friends in the wake of Stephen's murder.