An urgent law change by the Government was made today to validate some speed limits set on roads since 2004.

Parliament has rammed through law changes in just hours to validate tens of thousands of potentially illegal speeding tickets.

The tickets were issued in up to 25 local government areas which may have failed to renew their speed limits from 2004, meaning all tickets issued on roads other than the open road for the last 11 years may have been invalid.

In a rare move, the Government back-dated the law changes to ensure no one could mount a legal challenge.

SUPPLIED Transport Minister Simon Bridges has pushed through law to retrospectively validate tens of thousands of speeding tickets.

It won the backing of every party in Parliament, ensuring the legislation was passed through all its stages under urgency with just two hours debate. Labour MP Phil Twyford labelled it "the fastest law making in the West".

Transport Minister Simon Bridges said roads that did not have speed limits renewed would have otherwise had 100kmh limits.

Technically, there were roads all around New Zealand with no speed limit, but Bridges said "that is not going to be the legal position because today this law is going to be retrospective."

He said it was not known how many drivers or infringement notices may be affected, but that was "a moot point".

He agreed there was "clearly a considerable number" of speeding tickets issued that could have been in a "legally uncertain" position, conceding it could have been tens of thousands, but said he did not have an idea of specific numbers and did not plan to look into it.

The issue was raised by the Kapiti Coast District Council about a month ago, when it became concerned its speed limit bylaw may have expired.

The council had not renewed its bylaws set in 2005 and they expired in 2012.

The council said it "misinterpreted" how often the bylaw needed to be updated.

"We're not happy that we made a mistake - but we're pleased the situation has been clarified for all of local government," council chief executive Pat Dougherty said.

Bridges said speed limits people had been following since the expiry of the relevant bylaws set by the local authority were those intended to be in place, and they had been followed and enforced "in good faith".

"Indeed, the law they were following is what it should have been, but possibly wasn't."

Up to 25 councils and road controlling authorities, such as the NZ Transport Agency, were potentially in the same position as the Kapiti council.

Bridges had not contacted those councils, but the Ministry of Transport was doing so on Tuesday afternoon.

"We haven't wanted to create serious legal uncertainty and a safety situation where obviously people might feel they can speed on our roads."

Bridges did not want "to get into the blame game" as to whose fault the blunder was, but said the law was clear enough that bylaws were required and needed to be reviewed - which some councils had done.

But a number of laws passed by Parliament meant the situation had not been as clear as it could have been, he said.

He denied the situation was embarrassing, but said it was "unfortunate" and "in a sense, worrying".

Changes had come before Parliament "on the first day we could get it here," he said.

Bridges introduced the Land Transport (Speed Limits Validation and Other Matters) Bill, which retrospectively confirmed local councils and road controlling authorities had the legal power to set speed limits.

It removes the requirement for councils to review speed limits five years after they are set, avoiding a repeat of the situation.

It also validates the speed limits set since 2004 and confirms that all enforcement actions taken under those bylaws are valid.

It is not the first time MPs have used urgency to fix legislative mistakes.

In October 2013, Parliament passed a legislative fix to stop defendants challenging their arrests.

The amendment to the Policing Act passed after three hours of debate. It validated the oath of 63 officers who rejoined the force between 2009 and 2013.

The mistake came about after a law in 2008 changed how officers were sworn in, saying it could only be done by the commissioner.

MPs passed emergency legislation in the previous parliamentary term after an error was discovered with oaths for new recruits. But the fix did not cover officers who rejoined the police force.

