The powers set out in the Bill are some of the broadest constitutionally important provisions ever seen in legislation. Clauses 7 (correcting power), 8 (compliance with international obligations power) and 9 (implementation power) are very broad Henry VIII clauses that, if passed, will confer on ministers extraordinary power to amend, repeal or replace elements of our statute book. Clause 9 even provides a power to enable ministers to modify the future EU (Withdrawal) Act itself.

Clause 7(1-2) provides for the minister to make regulations to remedy ‘deficiencies’ in EU law where the minister considers that the retained EU law contains ‘anything which has no practical application’ in relation to the UK or ‘is otherwise redundant or substantially redundant’. Clause 7(2) also sets out what the concept of ‘deficiencies’ might cover, providing some attempt at definitional criteria; but it further makes clear that these are illustrative, not exhaustive. The criteria ‘include (but are not limited to)’ the examples set out in the Bill.

What is considered a ‘deficiency’, a ‘redundant’ provision or of ‘no practical application’ is therefore open to wide interpretation. In short, it may be whatever the minister wishes it to mean. And ministers in different departments may interpret the terms differently, potentially introducing inconsistency into the post-exit statute book for which there will be no immediate parliamentary remedy.

Clause 7(5) indicates that regulations under this section may ‘(among other things)’ provide for functions of EU bodies to be exercised by a similar UK body or to be ‘replaced, abolished or otherwise modified’. Again, the term ‘among other things’ leaves the legislative door wide open.

Clause 17(1) provides that ‘A Minister of the Crown may by regulations make such provision as the Minister considers appropriate in consequence of this Act.’ Such an extensive power is hedged in by the fact that any provision must somehow relate to withdrawal from the EU, but given that this will arguably extend to every facet of national life, if granted it would, in effect, hand the government a legislative blank cheque.

The powers sought in the EU (Withdrawal) Bill are broad in scope and purpose but not unique when compared with some previous bills:

• The original text of what became the Legislative and Regulatory Reform Act 2006 proposed that a Minister might make provision by Order for ‘reforming legislation’ through amendment, repeal or replacement. Dubbed by the media and campaigners as the ‘Abolish Parliament’ bill, the legislation was subsequently revised so that it granted ministers by Order the ‘power to remove or reduce burdens’, with the definition of a ‘burden’ set out in a series of objective tests on the face of the bill. The final version of the legislation also imposed constraints on how the power could be used, along with a new form of strengthened parliamentary scrutiny in the Legislative Reform Order (LRO) procedure (see below).

• The draft Deregulation Bill introduced in 2013 would have granted ministers the power, by Order, to ‘disapply’ legislation deemed to be ‘no longer of practical use’. There was no objective test to determine this concept; it was whatever the minister’s judgement deemed it to be. Following scrutiny by a joint committee of both Houses, the government removed the clauses of concern in the final version of the bill.

• The Banking Bill, introduced in what were deemed ‘emergency’ circumstances in 2008, conferred power on ministers by Order to ‘disapply or modify the effect of a provision’ in delegated legislation or any Act of Parliament (except the Banking Act itself). It also proposed to ‘enable the Treasury to ‘make provision which has retrospective effect in so far as the Treasury consider it necessary or desirable for giving effect to the particular exercise of a power under this Act in connection with which the Order is made’.’ There was no known precedent in existing legislation for a power based on a minister’s perception of what was ‘desirable’ rather than ‘necessary’. During its passage through Parliament a restriction was placed on the face of the bill to the effect that the Treasury should ‘have regard to the fact that it is in the public interest to avoid retrospective legislation’. Otherwise, the powers survived the scrutiny process largely intact. No sunset clauses or strengthened scrutiny procedures were imposed.

• Both the Legislative and Regulatory Reform Bill in 2006 and the Public Bodies Bill in 2010 sought powers for ministers to abolish or create public bodies by Order, like the EU (Withdrawal) Bill. The Public Bodies Bill granted extensive powers to ministers to abolish or merge public bodies, modify their constitutional and funding arrangements, and transfer functions from one to another. These public bodies were largely created by primary legislation, and in some cases by Royal Charter.

To argue about which of these bills was the ‘worst’, because it contained the broadest, most far-reaching powers, is to miss the point. None of these bills is exactly comparable with another. The key point is that, as a result of the parliamentary scrutiny process, amendments resulted in the introduction of one or more of: objective criteria for, or a tighter definition of, the ways in which the powers might be used; sunset clauses; or strengthened scrutiny procedures.

Faced with the EU (Withdrawal Bill), the critical question for parliamentarians is thus what further limitations on its powers or enhanced scrutiny mechanisms can realistically be introduced, given the time constraints and unknown factors arising from the Brexit process.

To its credit, in the EU (Withdrawal) Bill the government has voluntarily introduced constraints on and sunset clauses for the powers it seeks, rather than being coerced to do so by the force of legislative amendment (particularly likely in the House of Lords).

The government’s proposed limitations are not perfect, but the frequent references - in the Delegated Powers Memorandum and Explanatory Notes that accompany the Bill - to the concerns and recommendations of the House of Lords Constitution Committee and Delegated Powers Committee attest to ministers’ efforts to engage constructively with what they know will be Parliament’s concerns.

Close attention needs to be paid to the text where words and phrases such as ‘deficiencies’, ‘no practical application’ and ‘otherwise redundant or substantially redundant’ are used. Parliament will need to satisfy itself that the government’s attempts at definition – for example, in Clause 7(2) in relation to ‘deficiencies in retained EU law’ – are sufficient, particularly given that the text makes clear that the use of the power may not be limited to the definition set out.

The government proposes to restrain the powers in Clauses 7-9 such that they cannot be used to make a retrospective provision; to create a relevant criminal offence (although what is deemed ‘relevant’ is unclear); or amend, repeal or revoke the Human Rights Act 1998. Additionally, the powers in Clauses 7 and 9 cannot be used to impose or increase taxation. According to the Delegated Powers Memorandum, this is a permitted exception for the Clause 8 power, but only where this is an appropriate way of preventing or remedying a breach in relation to compliance with the UK’s international obligations.

The restraints in the Legislative and Regulatory Reform Act 2006 constitute Parliament’s current ‘bottom line’ for the acceptable delegation of powers. Six safeguards were added to the Bill during its passage through Parliament. Thus, the powers could only be used if:

'(a) the policy objective intended to be secured by the provision could not be satisfactorily secured by non-legislative means;(b) the effect of the provision is proportionate to the policy objective;(c) the provision, taken as a whole, strikes a fair balance between the public interest and the interests of any person adversely affected by it;(d) the provision does not remove any necessary protection;(e) the provision does not prevent any person from continuing to exercise any right or freedom which that person might reasonably expect to continue to exercise;(f) the provision is not of constitutional significance.'

The 2006 Act also provided that the powers could not be used to impose, abolish or vary any tax; to create a new criminal offence; or to authorise forcible entry.

With respect to possible further constraints that might be introduced on the powers in the EU (Withdrawal) Bill, the precedents provided by (b), (d) and (e) above may be of particular relevance, given the concerns of civil society groups that the legislation will be used, for example, in a disproportionate way, or to roll back civil rights and environmental protections.

However, given that the government proposes that the Clause 7 power might be used - depending on what unfolds in the exit negotiations - to ‘modify, limit or remove’ the current reciprocal arrangements that apply to EU citizens living in the UK and UK citizens in the EU, the government would be unlikely to be keen on any provisions guarding against the removal of protections.

The correcting power in Clause 7 and the power for the purposes of complying with UK international obligations in Clause 8 will cease to apply two years after exit day.

Some campaign groups have argued for a shorter period, but sunset provisions in other legislation have often been longer – five years, for example, in the Public Bodies Bill. Two years may thus strike a reasonable balance. However, the fact that ‘exit day’ is not defined means that it remains unclear how long the powers might in fact remain in force.

The Clause 9 power to implement the withdrawal agreement will lapse on exit day. By definition, this power could only be used once the content of the withdrawal agreement is known. However, there could be a lack of clarity over when in the Brexit process this point is reached. This is because of the EU’s complex procedures for concluding international agreements, and uncertainty - encouraged by changing government language - over exactly when in the process the UK Parliament will vote on the withdrawal deal. There is a risk that the power could be used prior to any such parliamentary vote.

The clause could be made clearer if, for example, it stipulated that the power could not be used until both Houses had approved the withdrawal agreement. However, this could be highly contentious politically, owing to the government’s resistance to putting the promised UK parliamentary votes on a statutory basis, and Labour’s wish to pin the government down to allowing the UK Parliament to vote before the European Parliament does.

With respect to parliamentary scrutiny of the delegated legislation that will flow from the powers in the EU (Withdrawal) Act, the government has taken two steps which deserve a cautious welcome.

It has agreed to provide more detailed information than normal in the explanatory memorandums (EMs) that will accompany any statutory instruments (SIs) that flow from the powers in the Bill. The EMs will therefore explain what any relevant EU law did before exit day, and what is being changed and why; and confirm that the minister considers that the SI does no more than what is appropriate. The House of Lords Secondary Legislation Scrutiny Committee (SLSC) has previously raised concerns about the quality of EMs, because while they may be good at explaining what an SI does, they are often weaker in explaining why it is required, or what its effects are expected to be. Commitments to augment the EMs will therefore only be meaningful if the government provides EMs that fully reflect the SLSC’s guidance.

The government has also promised to lay draft SIs during passage of the Bill, so that parliamentarians can see how the government thinks it may need to use the powers the Bill contains, and scrutinise its approach accordingly. There are several early examples at the back of the Delegated Powers Memorandum, clearly designed to indicate that the government’s planned delegated legislation is purely technical in nature. Although this promise is welcome, to be practically useful the draft regulations need to be produced early enough for MPs and Peers properly to consider them. Previous governments have promised to lay draft regulations in relation to bills, but in practice have often done so late in the scrutiny process, and in some cases even as late as the morning of the relevant committee-stage debate.

Whatever these potential improvements, the form of parliamentary control proposed for the use of the powers in the Bill, as set out in Schedule 7, remains a significant problem. The more flexibility the government seeks in relation to the delegation of power to ministers, the greater the onus on it to facilitate effective scrutiny, to enable parliamentarians to hold it to account. Yet, on this score, the government offers nothing.

There are three important shortcomings in the government’s approach as set out in Schedule 7:

1. The government is in effect requiring Parliament to agree in advance to the specific scrutiny procedures that will apply to uses of the delegated powers in the Bill without knowing fully how the powers will be used.

The government acknowledges that it cannot fully define all the circumstances in which each power in the Bill will be used, because it does not yet know - and much will depend on - the outcome of the Brexit negotiations. However, in Schedule 7, it specifies the categories of SI that will attract the affirmative scrutiny procedure, in terms of the broad type of action for which they provide.

Parliament cannot be expected to agree to grant a power to ministers with a fixed scrutiny procedure attached, when it does not fully know how that power will be deployed. Parliament should therefore require that it, rather than ministers, decide the scrutiny mechanism for an SI, when it knows its scope and purpose.

2. The Bill explicitly defines the policy areas in which the affirmative procedure will be used. As a result, the government is in effect determining from the outset what it believes Parliament should debate.

This sits uneasily with its claims about the need for flexibility in other aspects of the process, and its apparent uncertainty about the full extent of the policy scope of some Brexit measures.

The affirmative procedure is the more rigorous of the two forms of scrutiny the Bill proposes for the powers it confers. In the House of Commons, SIs scrutinised according to the affirmative procedure are automatically referred to a Delegated Legislation Committee, where the matter can be debated for up to 90 minutes.

For all other policy areas where the EU (Withdrawal) Bill generates delegated legislation, the negative procedure will be the default scrutiny mechanism. Negative instruments are only debated if a Member ‘prays’ against them and the government grants parliamentary time for the debate - which it is not required to do, and which our research has shown it frequently fails to do, even when a debate is requested by the Leader of the Opposition.

The Bill provides that the affirmative procedure will be used for any Order which:

• establishes a public authority in the UK;

• provides for any function of an EU entity or public authority in a member state to be exercisable instead by a public authority in the UK established by regulations under section 7, 8 or 9 or Schedule 2;

• provides for any function of an EU entity or public authority in a member state of making an instrument of a legislative character to be exercisable instead by a public authority in the UK;

• imposes, or otherwise relates to, a fee in respect of a function exercisable by a public authority in the UK;

• creates, or widens the scope of, a criminal offence; or

• creates or amends a power to legislate.

The affirmative procedure is intended for those SIs likely to be of political and policy significance. Given the scope of the Brexit process, these six areas do not capture everything that MPs are likely to want to debate. For example, under the power in Clause 9, an SI regarding the reciprocal arrangements for UK and EU citizens would not be subject to the affirmative procedure. Whether there were a House of Commons debate on it would therefore depend on whether the government agreed to provide time.

3. The government’s proposed use of negative and affirmative procedures for SIs does not provide for adequate parliamentary oversight. We detailed the flaws in these procedures in our evidence to the House of Commons Procedure Committee in April 2017.

Beyond the standard negative and affirmative procedures, 11 strengthened scrutiny procedures already exist to choose from. These were expressly designed for circumstances such as these, in which Parliament cannot know how a power will be deployed and therefore cannot agree a scrutiny procedure for its use in advance.

However, in its approach to the EU (Withdrawal) Bill, the government has ignored these options. Other pieces of legislation which confer upon a minister a significant power to amend primary legislation – including the Acts highlighted above – have generally made the use of such a power subject to strengthened scrutiny processes. If it is not amended, the EU (Withdrawal) Bill will therefore provide for less rigorous parliamentary scrutiny than similar previous legislation, making for a step backwards in the legislature’s control of executive power.

Many of the 11 variants of the strengthened scrutiny procedure are rarely used. The three most commonly used ‘super-affirmative’ models are those attached to the making of Legislative Reform Orders (LROs); Public Bodies Orders (PBOs); and Remedial Orders.

Of these, the LRO procedure is the most rigorous, but it has the disadvantage of being time-consuming. It also gives Parliament a veto power. In the context of the Brexit process, both of these features may be potentially hazardous.

The PBO procedure is less time-consuming but it does not offer Parliament a veto.

In both the LRO and PBO processes, Parliament decides the level of scrutiny to be assigned to the SI in question. Both processes also allow for consultation, and involve scrutiny by an assigned committee that can make recommendations for amendment.

We have previously called for strengthened scrutiny procedures to be reviewed and consolidated, and have expressly opposed the creation of a 12th such procedure.

However, as a result of its unique nature (particularly the potential time constraints involved), the Brexit process may not readily lend itself to any of the existing procedures. Compromise may therefore be necessary.

The House of Lords Constitution Committee has already suggested that a Joint Committee of both Houses might be established to consider which level of the scrutiny hierarchy might be most appropriate for each SI created under the powers in the Bill. This may offer a solution, particularly for those SIs brought forward under significant time pressures.

Whatever else this Bill achieves, it has finally blown the lid off the delegated legislation process. The way in which Parliament deals with delegated powers and the delegated legislation that arises from them has long been widely regarded as deficient. But, the criticism notwithstanding, the issue has overall been regarded as ‘too difficult’, and the area is therefore one that has seen little reform.

As the nature and scope of public policy has become more complex, and the role of government has changed, this in turn has had an impact on the volume and scope of delegated legislation and its importance in the governance process. But, unlike the House of Lords, the House of Commons has not fundamentally altered the way it deals with delegated legislation to respond to these changes. As a consequence, modern legislation and regulation is being shoe-horned into an out-of-date scrutiny framework.

The political importance of the EU (Withdrawal) Bill means that MPs can no longer be indifferent to the delegated legislation process. They must finally take seriously their democratic responsibility for this legislation.

The immediate challenge is how to scrutinise the EU (Withdrawal) Bill and the SIs that flow from it. But good parliamentary scrutiny is not just for Brexit. Reverting to ‘business as usual’ for scrutiny of delegated legislation in the post-Brexit future would be unacceptable once MPs have finally confronted the realities. A new scrutiny system for all delegated legislation is thus required.

To address both the immediate and longer-term challenges, we will be publishing detailed proposals for a new ‘sift and scrutiny’ system at the beginning of September, to be available to MPs and Peers when they return after the 2017 summer recess.

Hansard Society (2017) The European Union (Withdrawal) Bill – initial reflections on the Bill’s delegated powers and delegated legislation (Hansard Society: London)