A detective who hit a teenager with his baton during a stop and search has been cleared of using unlawful force.
Det Con Kevin Rowley, 37, of the Met Police, was charged with the assault by beating of Tyrell Vassell following the incident outside a cafe in April.
It took place after the officer stopped two youths on Heath Park Road in Romford, east London.
Mobile phone footage taken by a member of the public was shown to Hendon Magistrates' Court.
The recording appeared to show Det Con Rowley striking Mr Vassell, then aged 17, as the teenager shouted, "you can't do this".
'Agitated and aggressive'
Prosecutor Arabella MacDonald said there was "no dispute that force was used", but argued what happened was an "unlawful application of force by violence".
However, District Judge Tan Ikram said the prosecution had not satisfied him that the force involved was unreasonable.
Det Con Rowley told the court he and another officer had been carrying out a stop and search after seeing Mr Vassell, now 18, holding a "wad of cash".
The detective said the teenager became "agitated and aggressive" and, despite trying to calm him down, "he just lost it".
"I had gone through handcuffs, verbal commands, knee strikes - my only option was to draw my baton," he said.
He said he struck the teenager "five times on the thigh as per our officer safety training".
Eyewitness Anthony Bailey told the court Det Con Rowley looked as if he was "trying to restrain" the teenager.
Mr Vassell was cautioned for a small amount of cannabis found on his person and subsequently arrested for obstruction of a drug search.
After the verdict, Met Police Federation chairman Ken Marsh said "a short clip of an incident does not always tell the full policing story".