Secondary legislation, the most common form of which is a statutory instrument (SI), is a form of law made by a government minister under powers delegated to them by a primary act of parliament.

While an act of parliament sets out the broad legal framework and principles, secondary legislation is used to fill in the necessary details and provide the practical measures to make the law work.

Thousands of statutory instruments are made each year, far outnumbering the number of primary acts passed by parliament. Approximately 3,500 SIs, generally labelled as rules or regulations, are made each year.

Secondary legislation is a flexible and essential tool of government, but its use and the limited level of parliamentary scrutiny mean they are sometimes the source of criticism. There is the option for limited consideration by parliamentarians, however, and they may also be subjected to judicial review.

Alongside SIs, there are several other types of secondary legislation.

Why is secondary legislation used?

While primary legislation establishes the main policy, secondary legislation can provide the technical and operational details. For example, an act might state that a particular industry must be licensed, while an SI would set out the specific license conditions and the application fee.

SIs can be made, amended or revoked much more quickly than primary legislation. This allows the government to be more adaptive in legislating, sometimes in response to changing circumstances.

It saves valuable parliamentary time by allowing ministers to handle detailed rules. This effectively frees up the House of Commons and House of Lords to focus on the major policy principles in primary legislation.

The date an act comes into force may also be the subject of secondary legislation.

Under the Misuse of Drugs Act 1971, for example, successive governments have used secondary legislation to ban new substances in response to new information about their perceived dangers.

SIs are published with an explanatory memorandum to outline their purpose and why the change is necessary.

Parliament’s role: scrutiny and the passage of secondary legislation

An SI becomes law after being laid before parliament and passing through one of two main procedural routes. The parent act specifies which procedure must be used for any SI made under its powers.

The negative resolution procedure

This is the most common procedure, used for the majority of SIs.

Under this procedure, the SI is laid before parliament and becomes law on the date stated within it. It then remains law unless either the House of Commons or the House of Lords passes a motion to annul it (known as a “prayer”), usually within a 40-day period. If no one objects to it or if a motion to object is not agreed to in a vote, the law continues in force.

A reported 80% of SIs are “authorised” under this procedure.

In practice, very few motions to annul are ever debated, and even fewer are passed. A fatal prayer has not been successful in the House of Commons since 1979.

It is more common for negative SIs to be debated in the House Lords. In the upper chamber, it only takes one peer to table a motion to ensure a debate. (Peers also table motions to “take note” of an SI, considering them in a non-fatal way.)

Crucially, the House of Lords retains the power to pass a “fatal motion” to veto an SI outright. This power is used exceptionally rarely, as it represents a direct confrontation with the elected government. But the Parliament Acts of 1911 and 1949, which successively established the legislative primacy of the commons, do not apply to secondary legislation.

The affirmative resolution procedure

This procedure is used for SIs that grant more significant powers, such as those that impose a tax or create a new public body.

Under this procedure, a draft of the SI is laid before parliament. But it cannot become law unless it is actively approved by a vote in both the House of Commons and the House of Lords. Unlike a standard bill, there is no requirement for one House to begin addressing the resolution before the other.

In this way, parliament can approve or reject an SI, but not amend it.

Scrutiny of secondary legislation: the role of committees

Given the limited time for debating SIs in the main chambers, the work of specialist parliamentary committees provides the main source of scrutiny.

The joint committee on statutory instruments (JCSI) is the cross-party committee of MPs and peers that conducts technical scrutiny of all SIs.

The JCSI does not consider the policy merits. Rather, it checks whether the SI is legally sound. For example, it checks if the SI complies with the powers given in its parent act and if its drafting is clear. It may make recommendations regarding an SI if it identifies an issue.

The House of Lords secondary legislation scrutiny committee (SLSC) conducts a policy scrutiny of SIs. It is responsible for drawing the special attention of the House to any SI that it considers to be “politically or legally important”, controversial or which gives ministers inappropriate powers.

The SLSC publishes a report each week, flagging any suspect SIs. Its reports often form the basis for debates in the Lords chamber. The SLSC must report within two weeks of an SI being laid before parliament.

The House of Lords cannot consider affirmative statutory instruments until both the JCSI and the SLSC have given their advice, which consider SIs in parallel.

The House of Commons statutory instrument select committee considers statutory instruments that are subject to commons procedure only, and determines whether they should be drawn to the special attention of the House.

What are ‘Henry VIII powers’?

The use of secondary legislation has become increasingly controversial in recent years.

Critics have raised alarm at the increasing use of “Henry VIII powers” in primary legislation. These are clauses that give ministers the power to use secondary legislation to amend or even repeal primary legislation. Critics argue that this represents a significant transfer of power from the legislature to the executive.

The House of Lords delegated powers and regulatory reform committee (DPRRC) defines a “Henry VIII power” as a “delegated power which enables a minister, by delegated legislation, to amend, repeal or otherwise alter the effect of an act of parliament”.

This is linked to the practice of so-called “skeleton bills” (or framework bills). This is where the government introduces primary legislation with very little substantive detail, leaving almost all the key policy measures to be filled in later by ministers using SIs. Critics see this as a way of dodging scrutiny.

The House of Lords delegated powers and regulatory reform committee defines skeleton bills as containing “skeleton clauses where the provision on the face of the bill is so insubstantial that the real operation of the act, or sections of an act, would be entirely by the regulations or orders made under it”.

A huge volume of SIs were used to deal with Brexit and the Covid-19 pandemic, making these criticisms more prevalent in political discourse.

On 6 January 2022, the House of Lords held a debate on the “increasing numbers of skeleton bills and the associated use of delegated powers within them”. Baroness Cavendish of Little Venice, a crossbench peer, said the debate was about “power and the damage done to ordinary people and democracy when the workings of power are hidden.”

House of Lords tax credits vote: peers take on Cameron (2015)

In 2015, the House of Lords voted to delay the government’s tax credit cuts, worth £4.4 billion, and compensate those affected in full. Under the government’s proposals, the income threshold for working tax credits (£6,420) would be cut to £3,850 a year from April.

The vote triggered a significant constitutional clash between the government and the upper house.

George Osborne, the then chancellor of the exchequer, chose to implement several billion pounds worth of cuts to tax credits through secondary legislation. This was a highly contentious move. Critics argued that the government was attempting to dodge scrutiny.

The House of Lords secondary legislation scrutiny committee responded with a highly critical report. Then, on 26 October 2015, the Lords voted by 307 to 277 to delay the implementation of the cuts until the government had conducted a full impact assessment.

The House also rejected a “fatal motion”, tabled by a Liberal Democrat peer, which would have blocked the changes entirely.

Baroness Meacher, a crossbench peer, told Sky News that the government was “pulling the rug” from under the feet of working people, saying the outcome sent a “powerful message” to MPs to think again.

The government, led by David Cameron as prime minister, reacted furiously. It accused the unelected Lords of breaching constitutional convention by blocking a financial measure passed by the elected House of Commons. Baroness Stowell, the leader of the House of Lords, invoked the long-established “financial primacy” of the House of Commons.

Osborne responded that the vote raised “constitutional issues”.

Faced with the intense political backlash, Osborne performed a complete U-turn a month later. In the autumn statement, Osborne announced that he was scrapping the proposed cuts entirely.

An official review (the Strathclyde review) was launched to consider curbing the powers of the House of Lords. The review ultimately recommended that the House of Commons be given the final say over secondary legislation. The Conservative government chose not to pursue the Strathclyde plan.

Baroness Evans, the leader of the House of Lords appointed by Theresa May as prime minister, announced in November 2016 that the government would not pursue the Strathclyde plan.

Baroness Evans told the Lords: “The government agree with my noble friend Lord Strathclyde’s conclusion that on statutory instruments, as with primary legislation, the will of the elected House should prevail…

“However we do not believe that we need to introduce primary legislation at this time. We recognise the valuable role of the House of Lords in scrutinising SIs, but there is no mechanism for the will of the elected House to prevail when they are considered, as is the case for primary legislation.

“The government are therefore reliant on the discipline and self-regulation that this House imposes upon itself.”

Proscription of Palestine Action by affirmative resolution (2025)

In July 2025, the government used secondary legislation to proscribe the direct-action group Palestine Action as a terrorist organisation. The move made membership of the group a criminal offence carrying a maximum 14-year prison sentence.

The Home Office accused the group of “aggressive and intimidatory attacks against businesses, institutions and the public”. However, civil liberties organisations argued proscription represented an overreach of state power and a threat to the right to protest.

The home secretary, Yvette Cooper, introduced the proscription via the Terrorism Act 2000 (Proscribed Organisations) (Amendment) Order 2025. It was subject to the affirmative resolution procedure, requiring an active vote of approval in both Houses.

Under the order, the government proscribed three distinct organisations at once. Palestine Action was grouped alongside two neo-Nazi organisations, namely the Maniacs Murder Cult and the Russian Imperial Movement.

Crucially, because parliament can only approve or reject an SI but cannot amend it, MPs and Peers were denied the opportunity to vote on the groups individually. MPs were instead presented with a choice to proscribe all three organisations together or to allow all three to remain legal.

In the House of Lords, Green peer Baroness Jones described the move as “sneaky”.

She said: “Collectively organising these three into one SI is perhaps a little bit sneaky of this government. Palestine Action is not like any other group that the British government have so far declared a terrorist organisation.”

Despite such objections, the House of Commons voted 385 to 26 to approve the order on 2 July 2025. The four Green MPs as well as a handful of Labour MPs considered to be on the left of the party voted against the SI.

The proscription came into force on 5 July 2025.

Between July and November 2025, approximately 2,500 individuals were arrested for showing support to Palestine Action.

Brexit and the EU (Withdrawal) Act 2018: ‘Henry VIII powers’ in action

The legal process of Brexit remains the single largest example of the use of secondary legislation in British history.

During Britain’s membership of the EU, a vast body of European law was integrated into its legal system. To ensure a functioning statute book after Brexit, this “retained EU law” needed to be amended.

The government’s solution was to grant itself sweeping powers in the EU (Withdrawal) Act to make these changes using SIs. This included extensive so-called “Henry VIII powers” – allowing ministers to use secondary legislation to alter primary legislation. The act gave ministers wide powers to make regulations to deal with “deficiencies in retained EU law” resulting from Brexit.

An example of a type of a legal deficiency was provided as “anything which has no practical application in relation to the United Kingdom or any part of it or is otherwise redundant or substantially redundant.”

Section 23 of the EU (Withdrawal) Act stated that ministers could “make such provision as the minister considers appropriate in consequence of this act”.

A 2017 Brexit white paper indicated that the corrections would require between 800 to 1000 statutory instruments.

The government argued this was a practical necessity to deal with the sheer volume and technical complexity of the required changes. However, the House of Lords constitution committee accused the government of sidelining parliament on an issue of immense national importance.

A constitution committee report, published in November 2018, stated: “Without a genuine risk of defeat, and no amendment possible, parliament is doing little more than rubber-stamping the government’s secondary legislation. This is constitutionally unacceptable.

“If the government’s current approach to delegated legislation persists, or the situation deteriorates further, the established constitutional restraint shown by the House of Lords towards secondary legislation may not be sustained.”

The 2018 act also led to the creation of the European statutory instruments committee to consider whether certain proposed negative statutory instruments used for legal revisions should instead follow the affirmative procedure. The committee had 10 sitting days to recommend whether the proposed negative statutory instrument should instead be subject to the affirmative procedure. The government did not have to follow the committees’ recommendations.

Between November 2018 and February 2019, the committee considered more than 30 instruments each month.

In March 2019, the Hansard Society estimated that 495 Brexit-related SIs had been laid since the passing of the EU (Withdrawal) Act.

In October 2023, the European statutory instrument committee recommended that the Data Protection (Fundamental Rights and Freedoms) (Amendment) Regulations 2023 (a statutory instrument) should be “upgraded” to be treated with an affirmative resolution in the commons. The committee found that the legislation would change the way that “fundamental rights” and “fundamental freedoms” are defined in UK data protection legislation.

The government accepted the recommendation, leading to consideration of the statutory instrument in the commons delegated legislation committee and the House of Lords grand committee. The regulations ultimately came into force as planned.

In 2023, referring to the use of SIs, a House of Lords library briefing found that some meant “small changes, such as removing references to ‘other member states’ from domestic law”. Whereas others were “more significant, such as removing EU state aid rules from domestic law.”

The Retained EU Law (Revocation and Reform) Act 2023 gave ministers (in both the UK and devolved governments) broad powers to revoke, replace and reform retained EU laws. Section 11 of the act allowed ministers to write a new domestic statutory instrument to replace a piece of retained EU law while ensuring the policy remains largely unchanged.

The 2018 law was focused on “deficiencies” in law arising from Brexit. The 2023 act focused more clearly on reform.

By the end of 2023, any untouched retained EU law was restyled as “assimilated law”. The act also ended the special status of retained EU law, meaning assimilated law would no longer be supreme over domestic UK legislation. This means that if a piece of assimilated law conflicts with a piece of domestic UK legislation, the UK law now generally takes precedence.

Section 12 of the act allowed ministers to restate assimilated law (excluding primary legislation). The deadline for this was outlined as 23 June 2026.

The government stated in 2023 that its statutory instruments were intended to maintain the status quo to tweak EU law to a UK context, for instance. The lack of a “bonfire” of EU law, as was originally proposed by the government, allowed for a more gradual, targeted approach.

The European statutory instruments committee was dissolved in September 2024 with its Brexit-specific function effectively concluded. It reportedly recommended an “upgrade” from the negative to the affirmative procedure for approximately 20% of all instruments it considered.

Additional resources

• Legislation.gov.uk – Statutory Instruments: https://www.legislation.gov.uk/ukdsi
• Statutory Instruments (Joint Committee): https://committees.parliament.uk/committee/148/statutory-instruments-joint-committee/
• Secondary Legislation Scrutiny Committee: https://committees.parliament.uk/committee/255/secondary-legislation-scrutiny-committee
• House of Commons Information Office – Statutory Instruments: https://www.parliament.uk/globalassets/documents/commons-information-office/l07.pdf
• House of Lords Library – Skeleton bills and delegated powers: https://lordslibrary.parliament.uk/skeleton-bills-and-delegated-powers/
• Guidance to the Public on writing to the House of Lords’ Secondary Legislation Scrutiny Committee: https://www.parliament.uk/globalassets/documents/lords-committees/secondary-legislation-scrutiny-committee/public-slscguidance-july-2016.pdf
• REUL (Revocation and Reform) Act 2023 statutory instruments: https://www.gov.uk/government/collections/reul-revocation-and-reform-act-2023-statutory-instruments