It can be hard to keep perspective when an incident as devastating as the Christchurch earthquake occurs.

The natural urge is to ensure rebuilding proceeds as quickly and as smoothly as possible.

In the process, it is possible to overlook niceties and even to go where, constitutionally, governments should not tread.

That, regrettably, has happened in the haste to pass the Canterbury Earthquake Response and Recovery Bill.

This legislation, enacted in a day with the backing of all parties, creates an order-in-council mechanism.

This allows ministers to relax or suspend potentially every other act of Parliament - barring five dealing with constitutional matters - to the extent they may "divert resources away from the effort to efficiently respond to the damage caused by the Canterbury earthquake".

It also creates the Canterbury Earthquake Commission, which comprises the mayors of Christchurch, Selwyn and Waimakariri and four Government-appointed commissioners.

It will advise the Government what orders-in-council are needed to speed up rebuilding. Orders must be signed off by the Cabinet and the Governor-General.

They will, however, not be able to "be challenged, reviewed, quashed, or called into question in any court".

These extraordinary powers are potentially far-reaching. Effectively, Parliament has handed over its normal law-making role to the Executive. And it has done this while also sacrificing the precept of judicial scrutiny.

Rarely should either be contemplated, no matter how dire the crisis. In this case, an earthquake has triggered a law that goes far beyond what is required to get things done in Christchurch.

The justification offered by Earthquake Recovery Minister Gerry Brownlee is that "business as usual won't work". That is true and strands of red tape embedded in the likes of building law needed to be stripped away. But not to this degree.

The Government should have passed a tightly focused law, which could be broadened if road-blocks persisted.

Although the potential is there, it is highly unlikely the Government will be tempted to use its emergency powers in areas other than the rebuilding. Indeed, the legislation says orders-in-council must "take into account the purpose of this act". That, however, is a fairly elastic concept.

The only real safeguard is media vigilance and public outrage over any misuse of the law; for example, the go-ahead for infrastructure or buildings that before the earthquake were attracting strong opposition.

Much to their credit, the Greens suggested amendments that would have made the law more palatable. These included orders-in-council being made public within 24 hours, confining the legislation's override powers to identified acts, and a six-month sunset clause.

None of these was adopted, although the Government did, after consulting Labour, agree on the act terminating in April 2012, not 2015, as originally intended.

That offers little solace. Clearly, parties that saw the bill's shortcomings were in a bind. Opposing the legislation outright would have been interpreted as kicking Cantabrians while they were down.

It would also have run counter to the need for national unity. Parliament acted just 10 days after the earthquake and, significantly, without input from the likes of the Law Commission.

After the 1931 Napier earthquake, in which 256 people died, the Government appointed two commissioners to oversee reconstruction. No excessive laws were passed.

The approach succeeded admirably. Much has changed since then and the parallels with Christchurch are far from exact. Nonetheless, laws passed in haste, without consultation, are invariably flawed.

Laws removing checks and balances on the Executive require exceptional public scrutiny. National's ministers will need to be watched carefully.