Police were right to use a Taser against a man who was threatening to cut his own throat during an incident at Carrickfergus in March 2010, the Police Ombudsman has found.
Al Hutchinson said the use of the weapon had been necessary and justified, and had been used correctly in order to prevent death or serious injury.
He also found that police had used the Taser only when other options for resolving the situation had been tried and failed.
The incident began shortly after 1am on 6 March 2010 when police received a report about a fight at a house in the town. The caller said someone may have been stabbed.
Police arrived at the house 14 minutes later and spoke to a male and a female. The male had been stabbed, and told police that a man had made off from the scene armed with a bread knife.
Police quickly located the man in a nearby garden, holding the knife to his own throat. He threatened to kill himself if police approached.
The five police officers at the scene tried to calm the man down and kept him talking until the arrival of an additional five trained firearms officers about half an hour later.
At 2.15am police requested that a trained negotiator be called to talk to the man, but at 2.22am the man said he was going to cut his throat in two minutes. Officers recalled the man becoming more agitated before stating that he was going to slit his throat in 40 seconds.
The armed officers moved towards him and asked him to drop the knife. He was also warned that a Taser was aimed at him. The man then raised the knife to his throat and made a slashing motion, at which point an officer shouted "Taser, Taser" and discharged his weapon.
The shot struck the man and allowed officers to move in and disarm him. An ambulance arrived a short time later and took the man to hospital where he was examined by a doctor.
When later interviewed, the officer who discharged the Taser said he did so only after other means of trying to resolve the situation had been tried and failed. He said he was aware that the man was intoxicated and was suffering from some mental health issues.
Police Ombudsman investigators visited the scene and later obtained statements from all of the officers who had been involved. Letters appealing for witnesses were delivered to homes in the area, and PSNI documentation, including logs of information available to police and the actions they took, were examined.
They also established that the officer who used the Taser was properly trained and authorised to use the weapon at the time of the discharge.
Concluding that none of the officers involved had committed any criminal or misconduct offences, Mr Hutchinson said: "Police used a graduated response, starting with verbally reasoning with the man, giving him opportunities to surrender the knife and warning him that Taser would be used, prior to its discharge.
"The reason for police attendance at the scene was to disarm Man A not only for the protection of residents in the area, but also for his own protection. In these circumstances the use of the Taser was the most viable option and helped achieve a successful outcome to the situation."