The Crown Prosecution Service is to review the case against eight police officers, following an inquest into the death of a man who had been restrained.
Roger Sylvester died after being restrained by police
Roger Sylvester, 30, died a week after being detained by eight Scotland Yard officers at his Tottenham home in 1999.
The inquest jury said he was unlawfully killed. He had been restrained too long, in the wrong position, it said.
The CPS had previously said no charges would be brought. The officers said they may appeal the inquest verdict.
A CPS spokesman said: "As with all inquest verdicts the CPS will review the case in light of all the evidence, including any new evidence given at the inquest and observations of the jury."
Mr Sylvester's family - who greeted the verdict with cheers and tears - said they were also considering their next steps.
They said they were considering whether to bring a civil prosecution, but hoped the CPS might bring charges.
They said they also hoped the police would change the way they trained officers to deal with people in custody.
Mr Sylvester's mother Sheila, 68, a retired nurse, said: "I'm very pleased at how it went today... We have had a lot to put up with and I have a lot to think about now."
Cousin Shirley Sylvester said: "I want their [the police] behaviour to be changed.
"Training is just one side of the coin and there has to be appropriate sanctions because that is part of this issue."
The Metropolitan Police said it was "naturally disappointed" with the verdict, but took Mr Sylvester's death "extremely seriously".
It added it was working on ways to reduce deaths in custody.
Restrained 'on front'
Mr Sylvester had suffered from mental health and drug problems, and was detained after being found naked and banging on the door of his own north London home on 11 January 1999.
Police detained the struggling man under the Mental Health Act and took him to an emergency psychiatric ward at St Anne's Hospital, Haringey, where he stopped breathing while under restraint.
He never recovered, and died seven days later in London's Whittington Hospital.
Pathologists at the inquest were unable to agree on the cause of death.
But the jury found Mr Sylvester died from brain damage and cardiac arrest, triggered and exacerbated by breathing problems which occurred during the restraint, and also cannabis-induced delirium.
The jury foreman said more force was used than was reasonably necessary, and said three points paid "a significant contribution to the adverse consequences of restraint".
"One - held in restraint position too long. Two - lack of medical attention. Three - no attempt was made to alter his position of restraint."
It was argued during the inquest at London's St Pancras Coroner's Court that Mr Sylvester was restrained on his stomach, which increases the risk of suffocation.
The officers denied the allegation, saying Mr Sylvester had been kept on his side in line with police restraint guidelines.
They also denied using excessive force, and indicated they may apply to the High Court for the verdict to be quashed and for a fresh inquest.
In a statement they said: "Their treatment of Mr Sylvester was motivated only by a desire to secure immediate medical intervention.
"This decision is likely to be the subject of further judicial proceedings."
All the officers are back at work and no disciplinary action has been taken against them.
The Police Complaints Authority said any decision on disciplinary issues would be delayed until the end of other proceedings.
David Lammy, Labour MP for Tottenham, who backed the Sylvester family throughout their four-year campaign for an inquest, said justice had been done but questions remained.
"Half a football team to restrain a man means that there are some very serious questions which need to be answered," he said.
The jury took two hours to reach a unanimous verdict after the month-long inquest.
Commander Phillip Hagon of the Metropolitan Police said: "We wish to reassure the family that the MPS has taken Mr Sylvester's death extremely seriously.
"We have endeavoured to listen to the family's concerns as well as the concerns of the wider community.
"We understand that this verdict may result in further inquiries and we will make every effort to assist with those inquires."
The Met had been taking various steps to try to reduce the number of deaths in custody, he said.
This included installing CCTV in cells, training custody sergeants, and continuing to work with "partner agencies and medical experts" to ensure appropriate treatment for people in custody.