The Public Accounts Committee will today hear evidence from Garda whistleblower Maurice McCabe about alleged corruption in the penalty points system.
The hearing, which will be held in private, comes despite calls from the Garda Commissioner and the Minister for Justice for it not to go ahead.
The PAC decided on Tuesday night to proceed with its inquiry, which will deal only with the loss to the taxpayer from problems with the penalty points system.
The Garda Ombudsman will investigate the allegations of Garda malpractice in the cancellation of penalty points and fixed charge notices, after Justice Minister Alan Shatter referred the matter to its office.