SHERBROOKE, Que. -- The Lac-Megantic railway disaster that killed 47 people was an accident and resulted from a perfect storm of unforeseeable events, the lawyer representing one of the accused in the tragedy said in his closing statements Tuesday.

Defence lawyer Charles Shearson told the 14 jurors they can't hold his client, train engineer Tom Harding, criminally responsible for an accident.

"In our society we condemn criminals," he said, wrapping up his final arguments on the last day of the trial, which began in October. "We don't condemn people for reasonable behaviour."

Quebec Superior Court Justice Gaetan Dumas is to give his instructions to the jurors Wednesday, after which they will begin deliberating on whether Harding and two other former railway employees are guilty of criminal negligence in the deaths of 47 people.

Harding, Richard Labrie and Jean Demaitre have all pleaded not guilty.

The Crown delivered closing arguments last week, as did lawyers representing Labrie and Demaitre.

Shearson told jurors that Montreal, Maine and Atlantic Railway, the now-bankrupt company that owned the train, did not strive for safety.

The railway's employees were not adequately trained, the company didn't conduct proper risk analyses of its railroad track and its employees didn't regularly perform brake tests that were perfectly in line with federal rules, he said.

On July 5, 2013, Harding parked the 73-wagon convoy on a downward slope in the town of Nantes, just outside Lac-Megantic. He kept the locomotive running and relied on air brakes and independent brakes, securing the train before leaving for the night, Shearson said.

However, a fire broke out on the locomotive and the firefighters who extinguished the flames turned off the engine, unknowingly compromising the braking system.

In the early hours of July 6, the oil-laden train began moving on its own, eventually derailing and exploding in Lac-Megantic.

Shearson said Harding admits to not conducting a proper brake test and failing to apply a sufficient number of handbrakes, which would have prevented the train from moving after its engine was shut off.

He suggested that evidence presented during the trial demonstrated MMA didn't require its employees to perform brake tests perfectly in line with the federal regulations.

Therefore, Harding's failure to apply the sufficient number of brakes was not a marked or reckless departure from reasonable conduct, Shearson said.

Harding could not have foreseen the locomotive would catch fire after he left for the night, he added.

"The events were completely unpredictable," Shearson said. "Everybody wanted to keep the focus on Tom Harding's conduct. But his conduct wasn't the cause of the accident. His actions were just one of the things that didn't prevent the accident."

Poor training, lack of risk analyses and a company culture that permitted employees to have the wrong reflex when parking trains were also critical factors to the derailment, Shearson said, as was the fire.

"I submit to you," he said, "that we have the perfect storm ... and we have no evidence as to what caused the fire."

Shearson said witness testimony during the trial demonstrated that other MMA employees showed a "pattern of non-perfect compliance" with the rules on brake tests.

"We can't hold people criminally responsible for not being perfect," he said.

Shearson added that Harding was alone the night he parked the train.

One-man crews on trains carrying dangerous goods were banned in Canada following the Lac-Megantic derailment.

"One-man crews are no longer allowed," Shearson said, referring to the rule imposed by the federal government shortly after the rail disaster.

"If it doesn't make a difference, then why take it away?"