On 21 October 2019 the UK government introduced the legislation required to deliver the Withdrawal Agreement and Political Declaration (WA) brought back from the EU Council meeting on 17 October. The government's aim is to complete all stages of scrutiny and debate in the House of Commons within three days, sending the approved Bill to the House of Lords on 25 October.

The crucial stage in the House of Commons is the Bill's second reading, scheduled for 22 October. If a Bill secures a majority at second reading then it is approved in principle. From that point, amendments may be made on points of detail, but not on more fundamental issues. Consequently, the second reading debate represents the only opportunity for opposition amendments to modify or soften the particularly "hard" Brexit contemplated by the WA. For example, the second reading debate would be the last real opportunity to press for a customs union with the EU, or for a confirmatory referendum on the terms of the proposed WA.

Opposition parties are also likely to raise strong objections to the Bill on the grounds that it seeks to provide Ministers with extensive "Henry VIII powers". Throughout the Bill, clauses empower Ministers to amend primary legislation (including the EU (Withdrawal) Act 2018) by means of secondary legislation. That approach will undoubtedly prompt concerns that passing the Bill would allow Ministers to make significant changes to the law on a range of issues, including Northern Ireland, without full Parliamentary scrutiny.

Schedule 5 to the Bill identifies which Regulations would be subject to a procedure requiring a positive House of Commons resolution before becoming law, and which would become law unless annulled by a negative vote in either House. Given that such Regulations would affect matters such as entry and residence rights, opposition parties are highly unlikely to be content with provisions that allow Ministers use that mechanism to make "any provision that could be made by an Act of Parliament".

Similar concerns are also likely to arise in relation to the government's approach to workers' rights in clause 34 and Schedule 4 to the Bill. Responding to opposition concerns during the 19 October debate, the Prime Minister and other members of the Cabinet repeatedly asserted that there would be no post-Brexit dilution of rights.

The basis for that statement appears to lie in Schedule 4, which introduces new provisions into the EU (Withdrawal Act 2018, requiring the Minister responsible for any post-Brexit Bill relating to workers' rights to make a "statement of non-regression". That statement would confirm the Minister's view that passing the relevant legislation would not result in the UK failing to confer on workers the benefit of any "workers' retained EU right". However, the new provision goes on to say that the Minister might alternatively:

make a statement to the effect that although the Minister is unable to make a statement of non-regression Her Majesty’s Government nevertheless wishes the House to proceed with the Bill.

This provision highlights the potential for a post-Brexit government with a working majority, and the inclination to do so, altering UK law in a way that would diminish workers' rights. The provisions of Schedule 4 are, to that extent, consistent with the 17 October amendments to the WA. Key changes included the relocation of wording to deal with regulatory alignment and "level playing fields" from the legally binding Withdrawal Agreement and into the more aspirational Political Declaration.

The Bill also incorporates and confirms the effect of the new Protocol on Northern Ireland, including the presumption that goods brought into Northern Ireland from any other part of the UK, or from any non-EU country, would be subject to EU tariffs and customs checks. That presumption would place the onus on businesses to show that goods are not "at risk" of entering the EU market through the Republic of Ireland. Similarly, as DexEu Secretary Steve Barclay confirmed to the House of Lords European Union Committee on 21 October that businesses in Northern Ireland would be required to complete summary export declarations in relation to goods moving from Northern Ireland to Great Britain. This, together with Michael Gove's statement in the House of Commons that it might prove necessary to restore direct rule in relation to Northern Ireland means that the vexed issue of the Irish Sea customs border will be a significant feature of this week's debates.

Political calculations will also, inevitably, loom large in the debates. Responding to a question on 19 October the Prime Minister indicated that the government would accept the "Nandy-Snell amendment" proposed in relation to the previous Withdrawal Agreement. That amendment would give Parliament a vote in relation to the government's negotiating mandate for the future UK-EU relationship. Although received as a significant concession, those seeking to rely on the "Nandy-Snell amendment" would need to be sure that its effect is not neutralised by the detailed provisions set out by clause 31 of the Bill. Section 31 introduces a new section 13C into the EU (Withdrawal) Act 2018. Any vote on the government's negotiating mandate would be triggered by a Ministerial statement of objectives. That statement must, by virtue of section 13C(3)

be consistent with the political declaration of 17 October 2019 referred to in Article 184 of the withdrawal agreement (negotiations on the future relationship)

The House of Commons would be called upon to pass a resolution approving the Ministerial statement of objectives. It would appear, from 13C(3), that the motion would not be capable of amendment, meaning that the government could not be required to depart from the position set out in the Political Declaration – including the clear potential for regulatory divergence.

Given those significant points of contention, it is highly unlikely that the Bill will sail through the House of Commons without protracted and heated debate. Meanwhile, the clock is ticking down to 31 October, with no guarantee of an extension should the legislation remain short of royal assent by that date. "No deal" remains a possibility, with only 9 days left for businesses to prepare.