Judith Vanessa Fleeting, 52, was on trial in the ACT Supreme Court charged with assault occasioning actual bodily harm.

The Crown alleged Ms Fleeting stabbed her son in the back in retaliation after he used a steak knife to put a hole in their last remaining bag of wine in the early hours of September 4, 2010.

But defence barrister Richard Thomas argued his client acted in self-defence after her son confronted her with a knife.

A jury of eight men and four women took just two hours to return a verdict of not-guilty this afternoon.

The court had heard Ms Fleeting and her son became very drunk after consuming at least 5 litres of boxed lambrusco, which they mixed with orange juice.

They went to sleep but Ms Fleeting was woken by loud music at about 4.30am and discovered her son drinking with his half-sister and a red-headed man known only as “Burgo”.

A screaming match ensued between mother and son over the presence of the half-sister, who was born out of an affair between Ms Fleeting’s ex-husband and another woman.

The Crown alleged the son grabbed a steak knife, telling his mother she had too much to drink, and stabbed the bag of wine.

Ms Fleeting was alleged to have stabbed her son as he walked away.

But the pensioner told the jury she was frightened for her life as her son approached her with the steak knife and the injury occurred during a struggle for the weapon.

Ms Fleeting told the court her son had been violent to her, flinging her phone down the hallway when she tried to call police, and had dragged her into the spare bedroom and shut her in.

Acting Justice John Nield thanked the jury for their service and discharged them.