TORONTO -- The Centre for Addiction and Mental Health was fined $80,000 Monday after pleading guilty to failing to implement procedures to protect a nurse from workplace violence.

It was one of four workplace safety charges against CAMH related to an incident in January 2014 at a facility in Toronto, where a nurse was beaten by a patient. The three other charges were withdrawn by the Ministry of Labour.

Line Forestier, the lawyer representing the ministry, said in an agreed statement of facts that the nurse was working the night shift when she was attacked.

She said the nurse was out patrolling the halls alone, when a patient grabbed her from behind, pushed her to the floor and beat her. As a result of the attack, the nurse suffered a fracture to her eye socket, impaired vision and post-traumatic stress disorder.

The nurse was wearing an alarm around her neck called a "screamer," Forestier read from the statement. But those alarms work by emitting a loud noise -- they aren't hardwired into the building's communications system -- and don't automatically trigger a building-wide alert.

Forestier said that a second nurse came to the first nurse's aid, and she now also suffers from PTSD related to the incident.

Neither of the nurses have been able to return to work in the two-and-a-half years since the incident, court heard.

Rob Little, the attorney representing CAMH, noted that since the incident, the procedure surrounding night patrols has changed. Now nurses patrol the halls in pairs, rather than individually.

Ontario Court Judge Robert Bigelow ordered CAMH to pay a fine of $80,000.

The Ministry of Labour had asked for a fine of $100,000.

Representatives from the Ontario Nurses Association and Ontario Public Service Employees Union, the unions that represent nurses at CAMH, said they weren't happy with the ruling.

They said that the hospital should have been fined the maximum allowed by the law -- $500,000 per charge.