Only half of police officers would report a colleague for beating up a suspect for attempting to escape arrest, a study into police ethics revealed today.
Just 54% of officers said they would definitely report a colleague who "punched a suspect a couple of times as a punishment for fleeing and resisting", the Open University survey found.
Some 4.2% of officers - nearly one in 20 - said they would "definitely not" report such behaviour, while 6.5% said they would "maybe not" report it, 21.2% said they would "maybe" report it and 13.1% remained neutral.
After presenting officers with 11 such scenarios, the report concluded that officers were not willing to report colleagues' actions even when they were certain that behaviours were against the rules.
In her report, Dr Louise Westmarland, senior lecturer in criminology at the Open University, said the findings show the "blue wall of silence still exists".
Presenting the survey at a conference on leadership and standards in the police service, "The study found officers were unlikely to report officers even in cases they thought were serious."
Elsewhere, one in five or 19% of officers said they would definitely not report a colleague who runs a private security business, while nearly one in five or 17.3% would "definitely not" report an officer who accepted unsolicited gifts on duty.
The survey also found that one in four officers would definitely not report an officer who accepted food and alcohol on occasions such as Christmas.
Dr Westmarland said the study also found that overall officers seemed "uncertain" as to what was "against the rules".
In the report, she said: "The findings of the study reveal that officers seem uncertain of the rules and regulations covering their behaviour, especially at the lower end of the spectrum.
"In other words, officers were not clear about the bending of rules covering minor offences such as working in their spare time or accepting free drinks or small gifts."
Officers who had been on the force for five years or less would report colleagues less often than expected, the report said, while officers who had been on the force 15 years or more would report the behaviour more often than expected.
The survey received responses from 520 police officers at three unidentified police forces, including a large force with major cities and mixed rural areas, a large metropolitan force with significant, largely isolated rural areas and a small rural force.