An RCMP officer who struck and killed a motorcyclist, then left the scene to drink vodka, testified in his self-defence T uesday, one day after his own lawyer told B.C. Supreme Court the officer is an alcoholic.

Cpl. Benjamin Monty Robinson is facing charges of attempting to obstruct justice after a fatal collision with 21-year-old motorcyclist Orion Hutchinson while off-duty in October 2008.

After the accident, Robinson handed his licence to a bystander and fled on foot to his nearby home. On returning to the scene, he told police he had two shots of vodka at home to calm his nerves.

The Crown alleges Robinson left the scene and drank the vodka in order to mask the extent of his impairment at the time of the accident and obstruct justice.

On the stand, Robinson denied trying to impact the investigation by drinking vodka, saying "I went for what has given me comfort."

Officer drank to 'dull the pain' of his job

Robinson also denied the claims of an unidentifiable Crown witness, who testified that some months before the collision, she heard Robinson advise people how to beat charges if they'd been drinking in an accident .

According to the witness, Robinson said they should leave their licence at the scene, find the nearest alcohol and drink it, to render any breathalyzer reading useless in court.

Orion Hutchinson was killed when his motorcycle collided with a Jeep. (Courtesy of the Hutchinson family/RCMP)

Tuesday morning Robinson, a member of the Osoyoos First Nation, testified that he drank "to dull the pain" of traumatic incidents throughout his career.

He testified he suffered night terrors and increased reliance on alcohol due to his involvement in the death of Robert Dziekanski at Vancouver International Airport in Oct. 2007 — a year before the fatal motorcycle accident.

Robinson testified media spin of the incident, in which he and three officers Tasered Dziekanski before he died, means people have preconcieved notions about him.

Expert testifies to alcoholism

Cpl. Robinson's claims of alcoholism were supported on Monday by Dr. Paul Sobey, an expert in addiction medicine. Sobey testified Robinson is a severe alcoholic with a number of relatives who suffer from substance abuse.

Sobey also told the court Robinson told him he had difficulty early in his career just having one or two drinks.

In cross examination, the Crown questioned the validity of Dr. Sobey's diagnosis, made just last month, from a four-hour meeting with Robinson, dealing with the officer's condition more than three years ago.

But Robinson's lawyer has promised more evidence to explain his client's actions, including testimony from a doctor who has been treating Robinson for post traumatic stress disorder since his involvement in the death of Robert Dziekanski .

Robinson and the other three RCMP officers who confronted and Tasered Dziekanski before he died are scheduled to stand trial on perjury charges in 2013.