The son of former Labour MEP, Proinsias De Rossa has been found not guilty by reason of insanity of assaulting his father at their Dublin home.
The jury at the Circuit Criminal Court in Dublin, heard evidence that 46-year-old Fearghal De Rossa had a psychotic illness and was suffering from delusions when he attacked his father in November 2011.
The court heard he had reduced his medication himself and was also drinking to excess.
The court was told the case was brought because Proinsias De Rossa felt he had no other way of getting his son to submit to proper psychiatric treatment.
Proinsias De Rossa had just returned from the inauguration of President Michael D Higgins on 11 November last year when his son began the attack.
Fearghal De Rossa told his father he was going to kill him and punched him repeatedly in the face before hitting him on the head with a shovel.
A witness told the court that he believed Mr De Rossa would not have stopped his attack if other people had not intervened.
Proinsias De Rossa was in hospital for six days afterwards.
The jury took just over 20 minutes to reach a unanimous verdict of not guilty by reason of insanity.
Fearghal De Rossa will now be detained in the Central Mental Hospital until further order.
Lawyers for Mr De Rossa told the court that Proinsias De Rossa wanted it to be said in court that the case was brought because he felt he had no other option to get his son to submit to proper psychiatric treatment.
He said he had tried other options but had not been successful.