An American woman who pleaded guilty to planning a Valentine's Day mass shooting at a Halifax mall failed in a bid to have evidence from Facebook postings excluded in the case against her.

Lindsay Kanitha Souvannarath pleaded guilty April 11 shortly after a Nova Scotia Supreme Court ruling that would have allowed the Facebook conversations between her and a co-accused and another man, now deceased, to be admissible. She had been scheduled to go on trial later this year.

Souvannarath was living in the Chicago area when she and two Nova Scotian men met online and planned the attack that was to take place at the Halifax Shopping Centre on Feb. 14, 2015.

Randall Steven Shepherd, her co-accused, pleaded guilty to the same charge last year and was sentenced in November to 10 years in prison, less 974 days for time served. A third suspect, 19-year-old James Gamble, was found dead in his parents' home as police closed in.

Souvannarath was arrested after flying to Halifax from Illinois. She was questioned by police and as a result, they contacted the police department in Geneva, Ill. and asked for help to seek a warrant compelling Facebook to produce records of the conversations associated with Souvannarath, Shepherd and Gamble.

Her lawyer argued that the warrant was based on statements that Souvannarath made to Halifax police after her arrest and were in violation of the Canadian Charter of Rights and Freedoms, as well as the 1963 Vienna Convention.

She wanted the Facebook evidence thrown out because the warrant was allegedly based on wrongfully acquired information.

Justice Peter Rosinski, in a written decision April 21, rejected the argument.

Nova Scotia courts have no say about whether search warrants issued in the United States comply with the Canadian Charter, he said.

He referred to a Supreme Court of Canada ruling that states "the Charter does not apply to non-Canadian authorities and cannot be so regarded by the courts" in this country.