“You can kill a man… and you can walk free. Not even a single night in prison. Just a slap on the wrist and a ticket to carry on with your life, like nothing ever happened,” former Boyzone star Keating wrote on Instagram on Thursday.
The court heard that Harte had sent a WhatsApp message shortly before the crash, but there was no evidence of phone activity at the time of the crash, which happened at about 3.35pm.
Harte had admitted taking cannabis a couple of nights before after tests showed trace elements of the drug in his blood.
Keating said the sentence was a “devastating example of a broken justice system, adding: “And then we wonder why we keep seeing this kind of behaviour on our roads, why people keep dying in road accidents across Ireland every week?
“It’s a joke and it’s morally corrupt that, rather than trying to fix our broken system, they all turn a blind eye.
“Shame on Dean Harte but, more so, shame on everyone involved in this process that contributed to the heartbreaking outcome for my family today. The Lord himself knows the injustice that was served, and the Keating family will never find peace. We will continue to fight for Ciaran’s justice.”
Road deaths in Ireland have been rising, in contrast to elsewhere in Europe. There were 178 fatalities recorded last year.
Last week, the UK government decided to lower the default speed limit on local rural roads from 80km/h to 60km/h in a bid to save lives.