A Met Police officer who knocked a teenager off a moped while employing a new ramming tactic could face criminal charges.
The officer carried out the so-called tactical contact to stop the 17-year-old from riding dangerously.
The boy, who was not wearing a helmet, was admitted to hospital with serious head injuries but later discharged.
A decision is due over whether evidence gathered by the police watchdog should be passed to prosecutors.
If he is prosecuted, the officer could be charged with actual bodily harm or grievous bodily harm.
The Met could also decide if there is a case to answer for misconduct, which could result in dismissal.
‘Impunity not guaranteed’
An investigation by the Independent Office for Police Conduct (IOPC) was launched after the crash in Eastern Way, Erith, at about 02:15 GMT on 7 November last year.
The boy later pleaded guilty to five offences at youth court, including theft, dangerous driving, and driving without a licence.
An IOPC spokesman said: “Ultimately no police tactic can ever be used with impunity in a country where we police by consent – be that tactical contact, the use of firearms or the use of restraint.
“It is always a matter of whether it’s reasonable and proportionate in the circumstances.
“But it would be wrong to offer guarantees in every case. Independent scrutiny is a vital part of public confidence in the way policing is done.”
The watchdog also confirmed it was investigating a second tactical contact case involving another Met officer where an adult was taken off his moped in Ealing, west London, last March.
The tactic has been used 60 times since January by the Met in its fight against moped crime.
The force said there had been three injuries following pursuits by officers but not all were due to tactical contact. The Met said it had self-referred all instances to the IOPC.
Senior officers have defended the use of tactical contact, saying it was needed to stop dangerous chases and has helped reduce moped crime in London by more than a third.
The manoeuvre has also been backed by Prime Minister Theresa May, who said a “robust” response was needed from police to what she described as a growing problem of people using mopeds to commit crimes such as bag and phone-snatching.
But Labour has raised concerns about the approach, which shadow home secretary Diane Abbott said was “potentially very dangerous”.