Police say the officer was involved in a traffic stop last May when a 20-year-old man approached him.
Police say the constable struck the man while arresting him for public intoxication and the man fell and hit his head on the pavement.
He was taken to hospital and released a short time later, although he returned later in the day and was treated for a serious head injury.
The Crown reviewed an investigation into the officer's conduct and recommended he be charged.
David John Easter, who is 38, is to appear in court Feb. 13 on a charge of assault causing bodily harm.
The 14-year veteran has been relieved from duty, with pay, pending the outcome of the court case and an internal disciplinary hearing.
Charges against the alleged victim of obstructing a peace officer and resisting arrest remain before the courts.
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