A veteran Calgary lawyer says Douglas Garland's defence strategy is a tactical decision, possibly based on a belief the Crown has failed to prove its case.

Garland's defence lawyers told the court Thursday that they would not be calling any evidence in the triple-murder trial.

The 57-year-old is charged with three counts of first-degree murder, accused of killing five-year-old Nathan O'Brien and his grandparents, Alvin and Kathy Liknes.

"It is not absolutely unheard of," Don MacLeod told CBC Calgary News at 6 on Thursday.

"Trials of course are inherently risky exercises. The defence always, in this country, rests on the notion that the Crown must prove each and every element of its case beyond a reasonable doubt."

MacLeod says it's a calculated gamble.

"It is quite possible that the defence, in any jury trial, looks at the Crown's case and says, 'There is a gap somewhere here, there is an absence of evidence, the Crown has failed to meet that overarching burden and says to itself, we are not in a position where we have to call evidence,'" he explains.

It could be the defence feels there's a good case for a new trial, MacLeod added.

"There may also be issues around the path along the way, particularly in a very complex trial where evidence has gone before the jury that the defence feels reflects an error of law that may lead to a new trial down the road. In those scenarios there may be a tactical decision made even at this early stage."

'Your first homicide case is one that you will never forget'

MacLeod says the case has been hard for everyone involved.

"It can be very difficult. Speaking as a lawyer, your first homicide case is one that you never forget. It is burnt into the hard drive," he explained.

"Even seemingly hardened police officers will find [the details] traumatizing, disturbing, something that sticks with them a very long time and are known to seek out counselling internally within their police service."

In the Garland trial, the jury has been dismissed until Monday morning when closing arguments will be made.

With files from Meghan Grant