Parliamentary ‘ping-pong’ refers to the phenomenon whereby disagreements between the House of Commons and the House of Lords sees a bill travel back and forth between the lower and upper chamber.

‘Ping-pong’, an entirely informal term, occurs when one House has made amendments that the other refuses to accept. The bill is then sent back and forth between the two chambers until either the bill is lost, an agreed text is finalised or the deadlock is forcibly broken by the 1911 and 1949 Parliament Acts.

The process of ‘ping pong’ typically involves the House of Lords taking a resistant stance on a proposed piece of legislation, refusing – at least temporarily – to defer to the primacy of the commons.

The ‘ping-pong’ process

After a bill has passed all its stages in the House of Commons, it is sent to the House of Lords for further scrutiny. The Lords may make amendments to the bill, which are then sent back to the commons for consideration.

The House of Commons then debates the amendments agreed by peers. For each amendment, the government will table a motion to either:

• Accept the Lords’ amendment exactly as it is.
• Reject the Lords’ amendment entirely. MPs do this by agreeing to the question “That this House disagrees with the Lords in the said amendment”.
• Accept the amendment but make consequential amendments to other parts of the bill to ensure the whole law still makes sense.
• Accept the Lords’ change but amend their specific wording before agreeing to it.
• Accept the Lords’ amendment but transfer the new text to a different place in the bill.
• Reject the Lords’ amendment but suggest a different version instead (an amendment in lieu).
• Divide a single Lords amendment into parts to vote on them separately (e.g agree to one half, but disagree with the other).

If the commons disagrees with a Lords’ amendment, it must provide a formal justification. A reasons committee, usually a small group of ministers and whips, is immediately formed to draw up the official “reasons” for the commons decision to deny the amendment.

The bill, along with the reasons, is then sent back to the Lords.

The House of Lords then considers the position taken by the commons. It can choose to:

• Not insist and let the original amendment drop (this leads to agreement).
• Not insist but suggest a new version (amendment in lieu) instead.
• Insist on their original amendment and provide a formal reason for doing so.
• Agree, reject, or tweak any commons changes by proposing further/consequential amendments to them.

If the Lords insists on its amendment or proposes a new one, the bill is sent back to the commons, and the process repeats. This back-and-forth can continue for several rounds. Ping-pong often involves multiple amendments to the same bill moving back and forth at once.

Alongside this process, negotiations may take place between the government and the peers who proposed the amendment, with the aim of reaching a compromise and breaking the deadlock.

Ping-pong can also play out in the opposite direction if the bill begins in the Lords, although this is considerably rarer.

Moreover, while ping-pong can technically continue for several rounds, it may be limited by a convention known as “double insistence”. This is a deadlock reached when:

• House A insists on its original amendment.
• House B insists on its original disagreement to that amendment.
• Neither House offers an alternative proposal or a compromise (amendment in lieu or consequential amendment).

Double insistence is normally taken to indicate that the Bill has been rejected. But if each House continues to propose further amendments, the bicameral back-and-forth continues. Goodwill and negotiations usually means double insistence is not reached.

Erskine May, the authoritative account of parliamentary procedure, states: “In order to secure agreement and save the bill, every effort at compromise is usually made, and this interchange of amendments, as has been already stated, can be carried still further.”

It adds: “A bill is normally lost on ‘double insistence’. This is also referred to as ‘three shots at the same target’”

But according to Erskine May, there is no “binding rule of order” governing these proceedings, and if there is a desire to save a bill, the lower and upper chambers could come to some arrangement.

The European Parliamentary Elections Bill 1997-98 was lost to double insistence.

The primacy of the House of Commons

Crucially, the ping-pong process does not occur between two equal chambers. The powers of the unelected House of Lords are constitutionally limited.

The will of the commons, if there is a sustained majority in favour of a proposal, can always prevail over the House of Lords.

The 1911 and 1949 Parliament Acts provide a legislative backstop for the House of Commons if peers refuse to back down. The Parliament Act 1911, enacted following a constitutional crisis sparked by the Lords’ rejection of the 1909 People’s Budget, removed the upper chamber’s power of veto. The act established the primacy of the commons by replacing the Lords’ absolute veto with a power to delay bills for a maximum of two years, spread over three parliamentary sessions.

The act also removed the upper chamber’s power to veto any bill certified by the commons speaker as a “money bill”.

The Parliament Act 1949 further curtailed the power of the Lords by reducing its delaying power further to one year over two sessions. This was introduced by Clement Attlee’s post-war Labour government to prevent the Conservative-dominated Lords from obstructing its iron and steel nationalisation plans.

Resorting to the Parliament Act means a lengthy delay to the legislation, so there is still an incentive for the government to compromise.

The European Parliamentary Elections Act was ultimately passed after the government invoked the Parliament Acts of 1911 and 1949.

How does ping-pong end?

There are several possible ways ping-pong can end:

The Lords back down

Under pressure from the government, or out of concern that its powers could be further curtailed, the House of Lords may decide not to insist on its amendments, allowing the bill to pass in the form preferred by the House of Commons.

Compromise is reached

Through negotiation and compromise, both Houses agree on a final text for the bill.

The bill is lost

If the government cannot meet the requirements of the Parliament Acts because of time constraints, and no agreement is reached before the end of the parliamentary session, the bill is lost and fails to become law. The government would then need to reintroduce the bill from the beginning in the next session. Where there is no ‘next session’ – because a general election is imminent, for instance – the bill is effectively killed for the time being. As a result, the House of Lords is at its most powerful during the later stages of a parliament, when it can, in practice, exercise an effective veto through the ping-pong process.

The Parliament Acts are used

If the House of Lords continues to block a bill and the government is determined to proceed, it can reintroduce the bill in subsequent sessions and satisfy the provisions of the 1911 and 1949 Parliament Acts. The will of the commons thereby prevails over the obstinacy of the Lords.

Ping-pong in practice: the Safety of Rwanda Act 2024

The Safety of Rwanda Act 2024 passed despite significant opposition in the House of Lords after peers backed down.

The legislation was introduced after the supreme court ruled that the Conservative government’s Rwanda deportations scheme was unlawful. The court found that there were “substantial grounds for believing” that asylum seekers sent to Rwanda faced a “real risk of ill-treatment as a consequence of refoulement” – the practice of being returned to a country where they might face persecution or human rights abuses.

Rishi Sunak, the prime minister, unveiled a two-pronged strategy to overcome the court ruling: first, negotiate a new international treaty with Rwanda that would provide a legally binding guarantee against refoulement; and second, introduce emergency legislation that would enable parliament to confirm Rwanda as a safe country under UK law.

The subsequent Safety of Rwanda (Asylum and Immigration) Bill sought to disapply certain aspects of domestic law and the Human Rights Act 1998, and legally declare – for the purposes of the government’s deportation scheme – that Rwanda was a safe country. It directed decision-makers and court to “conclusively treat” Rwanda as a safe country.

The bill contained an “ouster clause” prohibiting a court from hearing a legal challenge to removal to Rwanda based on safety. A crucial element of the proposed legislation was that it would allow ministers to ignore the ECHR’s Rule 39 orders.

The bill passed its commons second reading by 313 votes to 269 – a majority of 44.

After the bill passed its commons third reading stage on 17 January 2024 (by 320 votes to 276), the prime minister, Rishi Sunak, called a press conference. He urged the House of Lords to accept the “will of the people”.

He said: “It’s now time for the Lords to pass this bill. This is an urgent national priority. The treaty with Rwanda is signed and the legislation which deems Rwanda a safe country has been passed unamended in our elected chamber.”

The bill faced determined opposition in the upper chamber. Peers repeatedly voted in favour of amendments intended to insert legal safeguards, exempt Afghan allies who had supported British forces from deportation and ensure the policy complied with domestic and international law. Each time the bill returned to the commons, however, the government used its majority to vote down the Lords’ amendments. The official “reasons” sent back to the Lords argued that the proposed changes were unnecessary as a commons majority considered that “the provisions of the bill are compliant with domestic and international obligations”.

The final standoff took place on 22 April 2024.

After several rounds, critical peers announced they would not insist on its amendments further.

Lord Anderson of Ipswich, a crossbench peer and former independent reviewer of terrorist legislation, had argued in favour of an amendment calling for a monitoring committee to advise on whether Rwanda is safe. Speaking at 11:57 pm on 22 April, Anderson stated that further opposition “did not command the necessary political support” and deferred to the “primacy of the elected house”.

He told the Lords: “The purpose of ping pong is to persuade the government through force of argument to come to the table and agree a compromise.

“They have refused pointedly to do so. And after four rounds of ping pong, the control of the commons remains as solid as ever. The time has now come to acknowledge the primacy of the elected House and to withdraw from the fray.”

The Safety of Rwanda Act thereby received royal assent on 25 April 2024.

Sunak, however, went on to call a general election for 4 July 2024. It meant the Rwanda deportations scheme was never fully operationalised.

Ping-pong in practice: the Representation of the People Act 1918

The passage of the Representation of the People Act 1918 came after a period of prolonged disagreement between the House of Commons and the House of Lords.

Although the act is best known for tripling the size of the electorate and extending the vote to women, its progress was repeatedly disrupted by disputes over electoral reform – particularly the introduction of proportional representation (PR) and the alternative vote (AV).

On 4 July 1917, following a heated debate, the House of Commons voted to remove provisions for PR by 201 votes to 169 – a majority of 32. MPs opted to retain the provision that proposed the introduction of AV in single-member constituencies. An amendment to strike out subsection two of the bill, which established the AV for single member constituencies, was defeated by 150 votes to 121.

When the bill reached the House of Lords in January 1918, peers reversed this position, voting to reinstate PR (by 131 votes to 42) and remove AV (by 57 votes to 9).

On 30 January, the commons then passed motions disagreeing with the Lords amendment proposing PR (by 223 votes to 113) and removing AV (by 178 votes to 170).

On 4 February, with parliamentary “ping pong” now in full flow, the Lords returned to consider the positions taken by the House of Commons on its amendments; the focus was once more on the proposed electoral system. The Earl of Selborne, the progenitor of the original PR amendment in the house of peers, proposed a compromise. He called for a more modest “experimental” scheme, applying PR only to boroughs returning three or more members – affecting roughly 141 seats. This scheme was approved by 86 votes to 35.

Meanwhile, AV was once again removed from the bill – this time by 66 votes to 29

On 5 February the commons voted to remove Selborne’s PR experiment by 238 votes to 141 – a majority of 97.

MPs also backed an amendment that would only apply AV to parliamentary boroughs (predominantly urban constituencies) by 195 votes to 194 – a majority of just one.

A final compromise was reached on 6 February 1918, the very last day of the parliamentary session. An agreement between the commons and Lords was now needed. Otherwise, the bill – including provisions granting returning soldiers the right to vote and extending the franchise to women – would have been lost. There was also little prospect that the commons would have had sufficient time to invoke the provisions of the Parliament Act 1911. The legislation required a bill to be passed in three successive sessions over a period of at least two years in order to bypass the Lords.

The Marquess of Lansdowne, a senior Conservative peer, therefore proposed a compromise. Instead of forcing proportional representation into the bill again, he suggested the creation of a royal commission to prepare a scheme for its future introduction. Lansdowne’s amendment was agreed without a division. Meanwhile, a motion to strike AV from the bill then passed by 74 votes to 33.

In the commons, an amendment to add AV to the scheme was ultimately rejected by 184 votes to 166 – a majority of 18. The Lords PR commission clause was then accepted by 224 votes to 114. MPs thereby abandoned AV, accepted a commission to consider a PR experiment, ended the parliamentary ping pong, and – at the eleventh hour – saved the bill.