A police dog called Bosko bit 56 people in an award-winning career, a court was told.
Police dogs are trained to restrain suspects
In one year the German Shepherd topped the Cleveland force's so-called Bites League, with 21 victims - including four police officers.
On Tuesday a teenager lost his case claiming damages for assault when he was bitten by Bosko.
The court was told that in December 2000 Bosko was used as a "dangerous weapon" when he bit a 14-year-old newspaper boy on both arms.
Hugh Tomlinson QC, prosecuting, told a jury that Ian Dawson, now 17, was attacked by the dog as he and a friend were "being nosey" around a dumped stolen car.
Mr Tomlinson said the teenage pair ran off when they saw Bosko's handler Pc Robson on the Grove Hill estate in Middlesbrough in December 2000.
He said Pc Robson unleashed eight-year-old Bosko who caught the teenager, inflicting bites and scratches to both arms.
His friend evaded capture.
The teenager, of Applegarth, Coulby Newham, Middlesbrough, needed treatment in hospital.
He was arrested on suspicion of vehicle taking without consent, but was never charged.
Pc Robson told the court: "In 1999 Bosko swept the board in the force competition.
"He took the trophies for every discipline.
"I retired him myself in 2001. If the boy had stopped when I shouted the dog would have sat in front of him and barked until I arrived.
"You can't teach a dog to bite softly, but he
will bite in a certain way.
"The only thing that tends to make a dog angry is if he is being beaten.
"If you were to lie still the dog would release you. If the person is fighting the dog tends to hold tight so as not to lose the prey."
Judge Peter Bowers ruled against the teenager.