An RCMP corporal on trial for obstruction of justice blames his severe alcohol dependence on his role in the use of a stun gun on a Polish immigrant.

Benjamin (Monty) Robinson, 41, took the witness stand Tuesday at his trial in B.C. Supreme Court in New Westminster.

Robinson is charged in connection with an unrelated incident that killed 21-year-old motorcyclist Orion Hutchinson.

He is best known for being one of four officers who were involved in using a Taser on Polish immigrant Robert Dziekanski at Vancouver International Airport in October 2007. The 40yearold died moments after being hit numerous times with a Taser.

On Tuesday, Robinson said his drinking increased after Dziekanski's death. The stun gun incident, followed by the release of a video documenting it, caused nightmares, terrors, sweats, nausea and flashbacks, he said. "It's like reliving a critical incident all over again," Robinson said. "I drank more to dull the pain."

He said people have preconceived notions about him because of the near-constant media attention and "negative spin."

"Five years of being under intense media and public scrutiny is trying," Robinson said.

The crash involving Hutchinson took place a year after Dziekanski died. On Oct. 25, 2008, Robinson took two of his children to a Halloween party at a friend's house in Delta. He testified he drank about five beers over four hours.

Defence lawyer David Crossin asked if Robinson felt fit to drive.

"Yes, I did," Robinson replied. Robinson said he had no concerns about his drinking and is confident his blood-alcohol reading was not over the legal limit.

While driving his children home, Robinson made a left turn about 10 p.m. and collided with Hutchinson. Hutchinson was thrown from his motorcycle and died at the scene.

After the crash, Robinson gave his driver's licence to a bystander and walked his children home. He did not try to help Hutchinson.

"My kids were there and I didn't want them to see the scene," Robinson said, adding that bystanders were attending to the motorcyclist.

After settling his kids, Robinson went downstairs to his bar and poured himself some vodka.

Crossin asked if Robinson drank to pervert the course of justice.

"Did you have that in your mind?" Crossin asked.

"No," Robinson replied.

On cross-examination, Crown prosecutor Kris Pechet suggested Robinson knew his admission to police that he drank vodka after the crash would "screw up" the investigation. Robinson agreed.

Pechet went on to suggest that Robinson misled police by minimizing how much he drank.

Robinson said he planned to tell police more but his lawyer advised against it.

Addiction specialist Dr. Paul Sobey testified Monday that Robinson suffered from severe alcohol dependence and depression in October 2008.