Minister for Transport Shane Ross accidentally voted against his own Road Traffic Bill in the Dáil today.
A spokesperson for the Government Chief Whip said Mr Ross highlighted his error immediately and the official record will be adjusted.
That will show that the minister backed the legislation despite his initial mistake.
Today's voting error by the minister has been described as "very unusual."
His spokesperson said Mr Ross "inadvertently pressed the wrong button."
The legislation, which the minister has been trying to bring through the Oireachtas for months, passed second stage in the Dáil by a margin of 85 in favour to eight against, with 37 abstaining.
The Bill provides for an automatic disqualification on a first offence for those convicted of driving while over the permitted limit of 50mg of alcohol per 100ml of blood.
The Bill will now be examined by an Oireachtas Committee.
Meanwhile, Fianna Fáil Chief Whip Michael Moynihan has said that his party will oppose the Bill at Committee Stage if the party's amendments are not accepted.
The party's TDs abstained in today's vote to allow the legislation move to the next stage.
However, Mr Moynihan insisted the party would vote against the legislation in the future if their concerns are not addressed.
Fianna Fáil is proposing a €500 fine and five penalty points for those caught drink driving with an alcohol limit of between 50mg and 80mg per 100ml.
The party remains opposed to the key measure in the legislation that will see these offenders given an automatic three month driving ban.