In the case of Gallagher v McGeady the Irish High Court ruled that the Plaintiff was guilty of contributory negligence in the amount of 40% for allowing herself to be a passenger in a car where the driver had consumed alcohol, and for not wearing a seatbelt, causing injury.
Ryan J had heard from Counsel that in cases where the passengers allowed themselves to be carried by persons under the influence there are decisions ranging from 30% to 50% Contributory Negligence, and in the worst case scenario there is precedent of up to 55% Contributory negligence for failure to wear a seatbelt. Unfortunately the judgement did not cite the relevant authorities quoted by Counsel in the case.
The leading case concerning a passenger in a vehicle driven by a drunk driver is Hussey v Twomey, a decision of the Supreme Court, reported by this blog here: http://laceysolicitors.typepad.com/insurance-law-ireland/2012/09/irl-recent-cases-in-pi-litigation-part-4-passenger-in-a-drink-driver-vehicle-the-case-of-hussey-v-twomey-and-others-20.html
The full judgement in Gallagher v McGeady can be read here:
Damian McGeady, Lacey Solicitors