Health and safety laws may be standing in the way of police officers showing bravery, according to the chief constable of Merseyside.
Mr Hogan-Howe said the police were already accountable for errors
Current law states that officers should assess risks and then take precautions before acting, Bernard Hogan-Howe said.
He fears safety rules may mean his officers standing back while passers-by were able to intervene.
Mr Hogan Howe defined bravery as when someone knows they may get hurt but still takes action.
His comments come after the Metropolitan Police were found guilty of breaching health and safety laws over the killing of Jean Charles de Menezes, who was shot several times at Stockwell Tube station.
At the time of the conviction Sir Chris Fox, former president of the Association of Chief Police Offices (ACPO), said that a sensible balance must be struck.
He said emergency response was "always more risky" when people did "incredibly brave and sometimes incredibly stupid things" to save others.
He added: "My fear is over-caution."
Jean Charles de Menezes was followed to train, then shot
The Merseyside chief constable echoed those fears, saying: "One of the definitions of bravery, for me, is when someone knowingly takes a risk. They know they may get hurt, but still they do it.
"Health and safety law says the police service, like all emergency services, should look at the risk involved and if there's a reasonable risk and they've put all the safety precautions in place can they then take it.
"That seems to be a contradiction and members of the public aren't governed by the same law.
"So we are faced with a terrible irony that in an emergency situation the police officer may have to turn to a bystander and say 'you may want to take action' - they then leap in while we are standing there worrying about it."
Mr Hogan-Howe said the police were already held to account for their actions through criminal and civil law, as well as their own misconduct process.
He added: "It does appear at the moment that we award a medal if things go well. But if an officer or member of the public gets hurt then there is a health and safety inquiry to see if someone should be hauled to account.
"These added health and safety pressures could open up the door to many other dilemmas."