The defence lawyer for a man charged in connection with a fatal 2012 wrong-way crash that killed a man and his daughter is asking for the case to be dismissed.

Sabastian Prosa's lawyer has filed an application for a stay of proceedings after he claims the blood sample that was submitted for independent testing was damaged.

Prosa is facing 12 charges, including impaired driving causing death, and has pleaded not guilty.

Police say on Aug. 5, 2012, the then-19-year-old was behind the wheel of an SUV that was travelling in the wrong direction on the QEW eastbound to Highway 427 northbound. The SUV struck a minivan, killing Jayantha Wijeratne, 49 and his 16-year-old daughter Eleesha. Wijeratne’s wife was also in the vehicle at the time of the head-on collision and was seriously injured. The family was returning from a vacation in Florida.

According to toxicology reports, Prosa's blood alcohol level was nearly twice the legal limit.

On Tuesday, the court heard that Prosa’s right to a fair trial was compromised after his blood sample that was sent to an interdependent lab for testing leaked because the cap wasn’t on tight enough. The sample was provided to the defence by the Centre of Forensic Science.

"The lost evidence has resulted in significant and substantial prejudice to the applicant. He is unable to make answers and defence to the charges against him. Fairness dictates that the proceedings ought to be stayed," lawyer Alan Gold told the court.

The defence says the leaked blood sample meant that it could not be tested for other substances such as GHB, or the date rape drug. They say it is possible the drug could have been slipped into Prosa’s drink prior to the crash without his knowledge.

Prosa is expected to take the stand in his own defence on Wednesday.

With a report from CTV Toronto's John Musselman