The Transport Minister cannot say if drivers who are stopped without a green card after Brexit will be prosecuted or have their vehicles seized.
Appearing before the Transport Committee, Shane Ross confirmed that Irish drivers who travel across the border into Northern Ireland would have to carry a green card to prove they are insured in the case of a no-deal Brexit.
However, Mr Ross was unable to give any clarity on whether motorists would face fines, disqualification or other penalties if they are stopped without the document.
Mr Ross said not having a card would "lead to problems" but said he did not know what penalties if any would apply.
"That is not clear yet...it will be clear in due course, it's not clear yet as to whether people will be prosecuted or not," he said.
Social Democrat TD Catherine Murphy pointed out that in some jurisdictions a person's car can be seized if they are stopped without insurance.
Committee chair Fergus O'Dowd said: "We need to get clarity for everybody. What is the legal position if you are stopped, for the public out there?
Mr O'Dowd said that people living in border regions should be automatically issued with a green card, but Mr Ross said that it would be up to insurance companies to make customers aware of the requirement.
Responding to questions from Fianna Fáil's Robert Troy, Mr Ross said he has no doubt that the OPW will have facilities in place at ports and airports by the end of March.
However, he added that "it's going to be a hurry, it will be difficult".