Almost six months after MPs backed the principle of assisted dying, the terminally ill adults (end of life) bill – sponsored by Labour backbencher Kim Leadbeater – is set to return to the House of Commons chamber on May 16 to undergo further debate.

This is the report stage of the bill’s passage, during which MPs will consider whether to make further amendments to the bill, followed by a third reading, when MPs vote on the bill in its final form. After this, the bill would then need to complete a similar process in the House of Lords.

There had been fears that because this is a backbench private member’s bill, the assisted dying bill would not be subjected to meaningful scrutiny. But these fears have not been borne out in practice.

Between January and March, a committee of MPs considered the bill over 29 separate sittings, heard evidence from around 50 expert witnesses, and received hundreds of written submissions from the public – all unheard of on backbench bills. The committee made many detailed amendments to the bill, informed partly by this evidence. It is the amended version of the bill that is now being put to MPs.

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When MPs debated the bill’s second reading in November, an absolute majority supported the legislation – by 330 to 275. But second reading is a vote only on the bill’s principle.

Several MPs indicated that they could vote the other way next time if changes were not made to the specifics of the legislation. So it is not certain that the bill will pass so easily at third reading – or indeed that it will pass at all.

During the bill’s committee scrutiny, over 150 amendments were made. Although the majority of these were put forward by Leadbeater herself – for instance to improve the bill’s operability after discussions with civil servants – around 40 of them were proposed by other MPs – including many led by MPs who voted against the bill at second reading.

They cover a range of topics, including the training for medical staff involved in assisted dying to identifying domestic abuse and coercive control, and a requirement that those considering an assisted death should be given information about palliative care alternatives.

Concerns raised by some disability groups have also led to a new requirement for a disability advisory board that will feed into the implementation of the law and report on its impact on disabled people. Such changes may provide some reassurance to wavering MPs.

But other issues remain unresolved. One example is the question of whether medical practitioners may raise assisted dying with a patient rather than leaving it to them. This is now the subject of a change proposed by Meg Hillier, the senior Labour MP who chairs the high-profile Liaison Committee and a vocal opponent of the bill.

A bumpy road ahead?

Even if MPs can agree on the text of the bill itself, it nonetheless faces significant procedural hurdles. This is because there is very little House of Commons time for private members’ bills – typically just 13 Fridays per annual session for all bills. This in practice means they must usually complete their report stage in a single five-hour sitting to stand any chance of passing.

The key challenge is that MPs could table large numbers of amendments, and speak at length, meaning that the bill runs out of time. The bill’s supporters can counter this by attempting to move the “closure” – which if successful brings that part of the debate to a close – but this requires at least 100 MPs to vote in support. This is a high threshold on most Fridays, though may be possible in this case.

Even then, it may not be enough. Much will depend on key decisions by the Speaker – in particular, how he groups the amendments up for debate. In recent years, the trend has been towards all amendments being discussed together in a single group.

But if he splits them up into more than one group, this would likely mean “closure” is required multiple times – creating a high risk that the debate overruns the available five hours.

If the bill does not complete report stage in a single day, it would then drop down the queue behind any other bills awaiting report on the next available Friday. This is usually fatal to a bill’s passage.

Yet something unusual may be about to occur in this case. As things stand, the next bill in line is scheduled to begin its committee stage only this week, after a long – and quite possibly tactical – delay. It is therefore possible that the assisted dying bill could secure a second day for report.

To the Lords…and back?

Yet any delay in the bill’s Commons passage would present further complications down the line. If the bill requires two days for report, this would push the final third reading vote to June 13 or 20. If it passed, the bill would then need to go through an equivalent series of stages in the House of Lords.

Lords scrutiny is likely to be rigorous on the bill. The chamber contains many members with expertise directly relevant to this bill – including medical, legal, disability advocacy and health. They are likely to want to scrutinise the bill in depth and to make their own amendments. Yet if peers make any changes, these would then need to be approved by the Commons.

As things stand, the last available sitting Friday for private members’ bills in the Commons is scheduled for July 11, potentially leaving less than a month for Lords scrutiny. This is a very tight timetable, and it is very possible the bill could run out of time.

One way of addressing this would be for the Lords to expedite its scrutiny of this bill. If not, ministers would need to provide additional time for any final Lords amendments to the bill to be considered – something for which there is recent precedent. Since 2010, two regular private members’ bills have had stages for MPs to approve Lords amendments (in 2019 and 2023); in both cases these required ministers to make available additional Fridays.

Daniel Gover does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.