Sabastian Prosa, who was 19 at the time of the horrific collision, is charged with two counts of impaired driving causing death and several other charges. If Justice Glenn Hainey rules the lost blood sample doesn't matter, he will deliver a ruling on those charges next month.
Prosa was behind the wheel of the GMC Envoy that struck the van carrying Jayanatha Wijeratne, along with his wife, Antonette, and their daughter, Eleesha, in August 2012.
Jayantha Wijeratne, 49, and his 16-year-old daughter died in the crash, while Antonette Wijeratne suffered severe injuries.
"I will be suffering for the rest of my life with my injuries," Antonette Wijeratne told reporters outside court on Wednesday.
Prosa, who has plead not guilty to all of the charges against him, admits to driving the vehicle that killed two members of the Wijeratne family, as well as to having almost double the legal limit of alcohol in his system.
But the accused testified during his trial that he believes someone spiked his drink when he was at a club on the evening of the fatal collision.
His lawyer, Alan Gold, has said a sample of Prosa's blood could not be tested because it leaked before it reached its destination.
Gold has argued that the lost blood sample impairs his client's ability to mount of full defence and has asked for all 12 charges, which includes two counts of impaired driving causing death, to be dropped as a result.
"We know the alcohol consumption. That consumption is unlikely to explain what happened... it's the involuntary consumption that caused what happened," he said in court.
But Crown prosecutor Tom Goddard argued in his closing argument Wednesday that Prosa willingly consumed up to nine shots that night.
"If you voluntarily become impaired and involuntarily become more impaired, that's not a defence," Goddard said.
"The ability to perform a test was lost but evidence was not lost. What's really lost is a Hail Mary attempt. A hope."
Justice Hainey will have to decide whether Prosa's charter rights were breached by the problem with the blood sample.
If he's not convinced that is the case, Hainey will then rule on whether Prosa is guilty or not guilty.
Hainey is expected to have a decision on both the charges and the breach application on May 27.
Watch the video above to see a full report from the CBC's Michelle Cheung.