A sunset solution?

There's no way that Labour would implement this now, but it's something that the next third-term government should seriously consider.

Any incoming government has a big platform it wants to implement. Some of it will be well thought-through; some of it will be off the cuff dumb promises made in the heat of an election campaign.

And policy passed in haste as part of an incoming government's 100-day plan will never get the kind of rigorous treatment in an RIS process that it should. That would be true even if Treasury hadn't diverted all computer power over to trying to measure happiness, much like the Starship Heart of Gold's computer being fully occupied in trying to figure out how to synthesize tea while missiles from Magrathea approached at speed.

A potential solution? Sunset clauses. Something like this:

All legislation and regulation must be accompanied by an adequate Regulatory Impact Assessment. Where haste prevents the an adequate RIS from being produced, that legislation or regulation must include a sunset clause voiding the policy two years after its implementation and mandating a Post-Implementation Review to be completed within eighteen months of the the policy's initiation. That would be followed by an amendment bill to the original legislation. A successful PIR would have the amendment bill simply remove the original sunset clause. But a PIR finding deficiencies, or failure to produce a PIR, could lead either to more substantial amendment or termination - with the default in case of no legislative action being the policy's termination under the sunset clause. 

A mid-term government could be pretty confident in doing this because it will impose far greater constraint on any incoming government than it imposes on itself. Mid-term governments have plenty of time to consider their legislative proposals; incoming governments try to make a pile of big changes in a hurry.

And an incoming government abolishing a requirement for sunset clauses could reasonably be asked by voters why it thinks its policies wouldn't stand up to post-implementation review.