The Nova Scotia Court of Appeal in Halifax reserved decision Tuesday after being asked to overturn the acquittal of a woman who admitted to hiring an undercover police officer to kill her husband.

Nicole Ryan, a high school teacher in southwestern Nova Scotia, was arrested in March 2008 and charged with counselling an undercover police officer to murder her husband, Michael Ryan.

In March 2010, a Nova Scotia Supreme Court judge found her not guilty on the grounds she feared for her life. 

At trial, Judge David Farrar accepted her evidence and that of other witnesses who painted the 40-year-old woman as a victim of years of spousal abuse, including threats at gunpoint.

Ryan testified at trial about a number of incidents between 2000 and 2004 when Michael Ryan, a member of the Canadian Armed Forces, threatened her with a gun.

Crown attorney Bill Delaney asked the province's highest court to throw out the verdict.

"At trial, Ms. Ryan was acquitted on a duress defence and the main point of our appeal is that duress did not apply in these circumstances," he said Tuesday.

The Crown is concerned that four months elapsed between the time Ryan paid what she thought was a hit man $10,000 and when she said she received the last death threat from her husband.

Defence lawyer Joel Pink said in court that years of abuse and the failure of the RCMP to intervene led his client to believe her husband would eventually kill her and their 10-year-old daughter, Aimee.

In 2007 there was a phone call that said not to "test me" and Aimee and Ryan would be destroyed and the house burned down, Pink told the court.

The marital home is still standing, but Ryan now lives with one of her sisters. Michael Ryan, who is retired and living in Ontario, has interim custody of their child.

A decision on the appeal will come at a later date.