Lawyer Zagi Kozarov worked at the Office of Public Prosecutions' specialist sex offender unit from 2009 until 2012 when PTSD and a major depressive disorder forced her to stop.

Supreme Court Justice Jane Dixon found her work dealing with sexual assault cases involving "gross depravity" was to blame for the disorder, and that her employers at the OPP breached their duty of care for Ms Kozarov.

She had felt she was not adequately supported or protected from the risk of psychiatric injury she faced and along with disturbing content, faced an intense workload.

Justice Dixon ordered a $435,000 payment of damages to Ms Kozarov, but that was overturned by the Court of Appeal on Tuesday.

Justice Dixon had found if the OPP had taken steps to reduce Ms Kozarov's exposure to vicarious trauma by August 2011 she would not have suffered post traumatic stress disorder of the same severity as she did when she left her job in February 2012.

She found if there had been a combination of adequate training, welfare intervention, flexibility regarding case allocation and rotations then Ms Kozarov's severe disorders would probably have been prevented from becoming so bad.

But the OPP said that conclusion was entirely speculative.

The Court of Appeal agreed, finding Ms Kozarov's circumstances in February 2012 were very different to what they were in the previous August.

On August 29, 2011 she sent an email advocating to remain in the serious sexual offences unit.

"I want to make it clear that I am passionate about continuing my work in the sexual offences unit and I don't want to leave the unit," she wrote.

In the following months she took time away from work and after being able to assess the effects of her work on her health she sought an immediate transfer in February 2012.

The judges said it couldn't be concluded that if the OPP had exercised the appropriate duty of care it would have resulted in Ms Kozarov accepting a rotation out of the unit.

The case must fail, they said.

Australian Associated Press