A trial began Thursday for Lethbridge Regional Police officer Const. Norman Smith, but ended a few hours later.
Smith was charged with assault and unlawful confinement of a 16-year-old boy during an arrest in December 2012.
The teen testified he was drunk and when the officer put him in handcuffs, he says the constable smashed his head on the back of a police car.
Smith, who is 33, had pleaded not guilty.