The trial has begun for a 37-year-old Beaconsfield woman accused of being drunk while driving a car involved in a deadly crash.

Stacey Snider was driving a BMW in Dorval on August 14, 2012 when she collided with an STM bus at the intersection of 55th Ave. and Lindsay Ave.

The impact knocked the bus on its side, killing two people and injuring ten others, some seriously, however Snider is not charged with dangerous driving causing death.

Snider's mother, Janet Stoddard Snider, 61, died at the scene, as did Sylvain Ferland, 49, the driver of the 196 bus. He was not wearing a seatbelt at the time and his body was pinned underneath the wreckage for four hours before it could be retrieved.

Snider, then 33 years old, suffered serious head injuries herself in the crash and a blood sample taken while she was unconscious is a key part of the evidence against her.

She was charged five months after the crash, but not with all the charges being recommended by police, due in part to the coroner's report into the crash.

Police were never able to establish whether Snider had caused the crash, or if Fernard had run a red light with the bus.

Snider's defence is that her charter rights were violated because she did not consent to the blood draw being used as evidence.

There is confusion about how much alcohol was in Snider's body. An initial report concluded she had a blood alcohol level of 0.240, or three times the legal limit, while a later report concluded she was only at 0.093 -- still well over the limit for driving.