The cancellation of the mid-February House of Commons recess to provide more time for scrutiny of Brexit legislation has elided uncomfortably with the fact that business in the Chamber has been light in recent days, so much so that the House adjourned mid-afternoon on Wednesday.

But there is more to legislative life than what goes on in the Chamber, and Brexit requires a lot more legislation than bills. Between now and 29th March the wheels of parliamentary scrutiny will have to grind relentlessly if parliament is to pass all the Statutory Instruments (SIs) necessary to prepare the statute book for exit day.

Statutory Instruments are pieces of delegated or secondary legislation used by ministers (and sometimes public bodies) to make changes to the law under powers conferred on them by an Act of Parliament.

The government estimates that it needs up to 600 SIs by 29th March. Yesterday the government laid its 400th Brexit SI since the EU (Withdrawal) Act received Royal Assent last summer. So the government is two-thirds of the way towards its goal.

But with 80 per cent of the parliamentary time to lay the SIs before exit day having elapsed, can the government get up to 200 more SIs onto the statute book before it’s too late?

The answer is yes, but it may be at some cost to the limited scrutiny that already takes place for SIs, particularly in the House of Commons.

The government has been laying an average of just 11 Brexit SIs per week, and has laid 25 or more in a week on just six occasions. In the last week of January it laid 36 Brexit SIs, but 24 of these were laid on the final day of the month. This pattern suggests that it will be a tall order, though certainly not impossible, to lay up to 200, at an average of 29 per week, in each of the remaining seven weeks to exit day.

There is precedent for laying lots of SIs quickly. For example, the government laid 303 SIs in the last month before parliament was dissolved for the 2015 general election; 121 of these were laid in the final week.

However, the majority of these were subject to the “negative scrutiny procedure,” rather than the more demanding “affirmative scrutiny procedure.”

SIs subject to the former do not require a debate or vote in both Houses before they can become law. And they routinely come into force before the 40-day scrutiny period, during which MPs can object to the SI, expires. In contrast, SIs subject to the latter procedure must be debated and formally approved by both the Commons and Lords before they can become law.

A critical factor in assessing prospects for the Brexit SI programme is that, in contrast to the normal pattern, the majority of Brexit SIs laid before parliament so far are subject to the affirmative procedure.

The current 53 per cent share of affirmatives among Brexit SIs is double what we normally see among SIs overall. This partly reflects the scrutiny safeguards built into the EU (Withdrawal) Act 2018, and partly the sifting process the Act introduced, which enables parliamentary sifting committees in both Houses to recommend that proposed negative SIs produced under the Act should be upgraded to the affirmative procedure.

In the House of Commons affirmative SIs are generally referred to a Delegated Legislation Committee (DLC) which debates the SI before the approval vote is then held in the Chamber on a subsequent day. Alternatively, affirmative SIs can be debated in the chamber rather than in committee, enabling the approval vote to take place immediately after the debate. In the House of Lords affirmative SIs are debated in Grand Committee or in the Chamber.

It’s the sheer number of debates on affirmative SIs that the government needs to hold in both Houses that is perhaps its biggest SI management challenge between now and exit day.

As of 7th February only half of these debates have been held in the House of Commons. Next week MPs will debate a further 12 Brexit SIs but there is still a backlog of 97 debates that have yet to be scheduled. Each debate has to be allocated up to 90-minutes (although they rarely last half an hour) and each requires up to 18 MPs including a chair, government minister, opposition spokesperson and clerks in attendance.

Just dealing with this backlog requires 14 Commons debates per week during each of the remaining sitting weeks. But if a majority of the up to 200 SIs that have not yet been laid before parliament are also subject to the affirmative procedure, then the number of debates needed will rise proportionately.

It is possible that the final number of Brexit SIs laid by the government might end up being nearer 500 than 600 which will ease the scrutiny burden. But if not, then MPs might, potentially, have to debate up to 80-100 more affirmative SIs on top of the backlog. A similar number of debates will be required in the House of Lords.

Here is where cancelling recess helps the government, as it gives ministers an additional few days on which they can both lay SIs and schedule debates. A group of related SIs can be grouped for consideration together, thus reducing the number of debates that need to be set up. But four extra sitting days is still unlikely to be enough. More time may be needed, so the prospect of Friday and weekend sittings cannot be ruled out.

What about the roughly half of Brexit SIs that are subject to the negative scrutiny procedure (which means that they do not require a debate or vote in both Houses)? Different combinations of procedures, laws and practices apply in relation to proposed and made negative Brexit SIs, and the scrutiny requirements vary.

As with other types of Brexit legislation, a lot depends on how far the government and parliamentarians are prepared to let “best practice” understandings about the amount of parliamentary scrutiny slide.

For example, even without the exigencies of Brexit, negative SIs routinely come into force before their 40-day scrutiny period has expired. In the 2015-16 session, for example, this applied to 80 per cent of negative SIs laid before parliament.

The government is, however, supposed to leave 21 days between laying a negative SI and bringing it into force. If the government were to respect this informal rule, pre-exit negative SIs would have to be laid by 9th March. Appearing before the House of Commons Procedure Committee this week, Brexit minister Chris Heaton-Harris MP said he expected that the remaining SIs would be laid in the next four weeks. If not, then this 21-day rule may have to be breached.

Even if the creation of extra parliamentary sitting time and the breaching of best practice rules were to prove insufficient, with respect to both negative and affirmative SIs the government still has a trump card. This is the urgent case procedure contained in the EU (Withdrawal) Act. The urgent procedure allows ministers to make SIs that come into immediate effect having been “made” (signed-off) by the minister. “Made affirmatives” require both Houses to approve them within 28 days to remain in force. As time runs out “made negatives” may be used to bypass the sifting process; these SIs would cease to have effect if either House annuls them within 40 days.

To use the urgent procedure, ministers will simply have to provide a written statement explaining the nature of the urgency. This will not be difficult in the circumstances. Ministers have said that they do not anticipate using the urgent procedure. But as a last resort it could be used to ensure that all SIs that are required can come into effect on 29th March.

However, for parliament, the scrutiny challenge would not go away—it would simply be pushed into April, when “made affirmatives” would have to be debated and approved.

In sum, the government can get the SIs it needs into law by exit day. But doing so may be at the expense of what limited scrutiny already takes place for SIs, particularly in the House of Commons, and might involve breaching rules and best practice commitments on how this type of legislation should be handled.

Joel Blackwell and Ruth Fox, Hansard Society