Saskatchewan's highest court has reinstated the original assault conviction of a Regina Police Service officer who kicked a homeless man and caused him to hit his head four years ago.

The recent Court of Appeal decision means Const. Robert Kenneth Power has been found guilty, not guilty and now guilty again.

After the original conviction, Power was sentenced to, and served, a year of probation.

Video footage showed incident

Security footage used as evidence in the original trial shows the incident, which occurred outside a detox centre. Court heard the man was an alcoholic whom Power had arrested or had dealings with about 100 times before.

On the night in question, May 7, 2012, the man got into a confrontation with Power, challenged him to a fight and moved toward the officer, court heard.

Power, who said he believed the man was HIV and hepatitis C-positive, kicked him in the chest or abdomen, knocking him down.

As he fell, the man hit his head on a cement wall, ending up with a bloody head injury that required hospitalization.

Security footage used as evidence in the trial of Rob Power appears to show the Regina police officer kicking a homeless man. (CBC)

The trial revolved around whether or not the 6-foot-1, 215-pound Power used reasonable force to stop the smaller, cognitively impaired, partially blind homeless man.

The conviction was appealed to the Court of Queen's Bench and was overturned. Power was reinstated as a police officer in December 2014.

The Crown appealed that acquittal to the Court of Appeal and on Tuesday, a written judgement reinstated the original assault conviction.

Justices split on decision

While two Court of Appeal judges agreed Power was guilty, a third had a dissenting opinion and said the kick was "not unreasonable" to repel an aggressor.

There's no word yet on whether or not the case will be appealed further, to the Supreme Court of Canada.