The trial of a Midland nurse charged with manslaughter for allegedly shutting off life support to her patient without permission is underway.

The Crown argued on Thursday that Joanna Flynn had no authority to remove Deanna Leblanc's life support on March 2, 2014. Leblanc died a short time later.

"Ms. Flynn overstepped her role on that day by venturing into an area reserved for physicians by terminating life support without a doctor's order," Crown attorney Sarah Tarcza told the jury in her opening statement.

Flynn was the intensive care nurse at Georgian Bay General Hospital that night. She's charged with manslaughter and criminal negligence causing death.

“It's not disputed that Flynn turned off the life support and that it resulted in Leblanc's death.  The issue is whether she committed an unlawful act causing Deanna Leblancs death, the Crown's position is that she did."

Tarcza told the court that Flynn coerced consent from Leblanc’s husband.

Leblanc was rushed to the hospital early that morning with medical complications two days after receiving knee surgery.

First to testify was the physician working in the emergency department when paramedics arrived at the hospital with Leblanc.

Dr. Gert van Rooyen told the court that Leblanc had “no vital signs" and "she had no blood pressure, no pulse."

Van Rooyen testified the emergency team took over CPR efforts from paramedics and continued for more than two hours having to restart at least five times. Van Rooyen also told the court Leblanc had the lowest score on a test that measures consciousness.

He also testified that he didn't recall receiving instructions from Leblanc's husband, while CPR was performed.

The doctor said Leblanc was eventually transferred to the intensive care unit hooked up to life support after she was able to maintain a pulse and blood pressure through medication.

The trial is scheduled to last eight weeks with testimony from Leblanc's family, hospital staff and medical experts.