The Supreme Court has quashed the decision of the then garda commissioner to dismiss a sergeant who had been convicted of assault from the force.

The court ruled that no adequate reasons were given by the then commissioner, Martin Callinan, for the decision to dismiss Sergeant Martha McEnery in March 2013.

Sgt McEnery had been in the force for 17 years and had been a sergeant for five years.

In August 2011 she was convicted at Waterford Circuit Court of one count of assault and later that year she was given a four-month suspended prison sentence.

She appealed her conviction but that appeal was rejected.

The then commissioner issued a notice to her in December 2012 that she was to be dismissed from the force because her criminal conduct was a breach of discipline.

Despite submissions from Sgt McEnery, that decision was confirmed in March 2013.

Sgt McEnery took her case to the High Court, which found against her.

However, the Court of Appeal ruled that the commissioner had not considered all the material facts and quashed the decision to fire her.

The Supreme Court has now upheld that outcome, but for a different reason - it found that when the commissioner confirmed his decision to sack Sgt McEnery in a letter of 25 March 2013, he should have given reasons for his decision, in order to comply with the principles of natural and constitutional justice.

Giving the court's judgment, Ms Justice Mary Laffoy said the commissioner did not rationalise any of his conclusions in the letter.

He merely reiterated his conclusion that her conduct merited dismissal in accordance with garda regulations.

She said he acted contrary to his implied duty under garda regulations and in breach of the principles of natural and constitutional justice and his decision should be quashed.

This evening, Garda Headquarters said: "Today's ruling is being considered by the Commissioner."