Could Lords inflict more humiliation on ministers over Illegal Migration Bill?

MPs have sent the Illegal Migration Bill back to the House of Lords after the government made a series of concessions designed to appease critics in the upper house. But we can expect a few more rounds of what is known as ping-pong, as the bill bounces between the two houses of parliament.

What has the government conceded so far?

It has dropped its plan to create unlimited powers to detain pregnant women, meaning the current 72-hour limit will continue to stand. The government has cut its power to hold unaccompanied child asylum seekers without bail to eight days – which is still longer than opposition politicians and charities called for.

Ministers have also abandoned their attempt to make the bill apply retrospectively to any small boat migrants who arrived after it was presented to parliament in March. That means that the “duty” on the home secretary to detain and deport people arriving on small boats will not kick in until the bill passes and receives royal assent, although the proposed ban on re-entry to the UK, settlement and citizenship will still apply retrospectively.

Will these changes be enough for the Lords?

Definitely not. The concessions should be seen as the opening bid in a long negotiation between the government and their opponents in both houses. Theresa May, the former prime minister, made clear on Tuesday that she remains opposed to the bill’s provision to stop migrants – regardless of how they arrived in the UK – claiming to be victims of slavery. “It will consign more people to modern slavery,” she told the Commons.

MPs then voted to reverse the Lords’ attempt to delete this clause, with May joining a small group of Conservative rebels refusing to support the government, but her strenuous opposition is likely to embolden peers to delete the clause again.

The Lords will probably drop their opposition to other measures in the bill, but will certainly reverse several of the government’s changes and send the bill back to the Commons a second time.

How far will the Lords push their opposition?

Many peers feel strongly about the bill, arguing that it is both morally deficient and likely to be ineffective. They note that the government has no electoral mandate for it, so they are likely to continue to make a small number of critical amendments repeatedly. They also know that the government is keen to pass the bill before the summer recess, which starts on 20 July. This gives them more leverage in the negotiations, which will mostly be conducted behind the scenes.

In the end, though, the constitutional convention is that the House of Lords will bow to the democratic authority of the lower house – once it feels it has made its arguments forcefully enough and once it has secured “improvements” in the legislation. Given that the government’s majority in the Commons is fairly solidly supportive of the bill, the government will get most of its way. Whether the law will be effective, though, is quite another question.