Fianna Fáil has questioned Michael Noonan's claim that its new bill to regulate mortgage rates is illegal.
The bill has been introduced tonight in the Dáil, and would give the Central Bank the power to limit variable rates if it sees fit.
The government says there might be constitutional problems with the bill, but is allowing it to pass at this stage.
But Fianna Fáil's Michael McGrath says it is a strange defence for the government to offer.
"When the legislation was originally debated in July of last year, the Minister did not raise any such concerns whatsoever.
"That debate was on the very same bill as the one we are debating tonight, presumably it went to the Attorney General for advice and no issues whatsoever were raised at that stage."