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How much legislation does the UK Parliament consider?

The law can change in two main ways:

• Through an Act of Parliament, where Parliament debates and agrees a bill. This is referred to as ‘primary legislation’.
• Through laws created by ministers (or other bodies) under powers given to them by an Act of Parliament. This is referred to as ‘secondary legislation’.

Bills can be introduced to Parliament by the government, and by individual MPs (these bills are known as ‘private members’ bills’).

This briefing provides data on acts, bills, and statutory legislation up to the July 2024 election.

For historic data, see Acts and Statutory Instruments: the volume of UK legislation 1850 to 2019.

Acts of Parliament

An act is a bill that has been approved by both the House of Commons and the House of Lords and which has received Royal Assent from the Monarch. Acts are also referred to as ‘primary legislation’. In the UK, there are four bodies that can pass acts:

• the UK Parliament
• the Scottish Parliament (see the Commons Library briefing Devolution in Scotland: “The settled will”? for more)
• the Senedd Cymru/Welsh Parliament, known as the National Assembly for Wales until the passage of the Senedd and Elections (Wales) Act 2020 (See the Commons Library briefing Devolution in Wales: “A process, not an event” for more)
• the Northern Ireland Assembly (see the Commons Library briefing Devolution in Northern Ireland for more)

The number of acts passed by these legislatures is shown in the graph below. The annual number of acts passed by the UK Parliament was higher historically, though the total number passed across all legislatures in the UK is comparable to this figure now. In the last 10 years of data, an average of 36 acts were passed by the UK Parliament.

Source: legislation.gov.uk. Note: Senedd Cymru also includes acts of the National Assembly for Wales. UK Parliament includes Public General Acts only.

Bills

Bills are proposals for new laws. If bills pass every stage of scrutiny in the House of Commons and House of Lords and receive Royal Assent from the Monarch, then they become Acts of Parliament. The graph below shows the number of public bills introduced to Parliament in each session in recent years.

Source: Parliamentary bills

As parliamentary sessions last for different amounts of time, looking only at the number of bills per session is potentially misleading. The graph below shows the number of bills per sitting day. This rate has increased, from just under one bill a day in the 2006-07 session, to around two bills a day since the 2019-21 session.

Source: Parliamentary bills, Number of sitting days in the House of Commons by session since 1900

Secondary legislation

Secondary legislation is law created by ministers (or other bodies) under powers given to them by an Act of Parliament. They are typically used to fill in the details of acts. Secondary legislation often requires statutory instruments (SIs), documents produced by government departments that make changes to the law.

The graph below shows the number of SIs produced by various UK authorities each year. The UK Parliament typically produces between 1,500 and 2,000 SIs each year. The exception to this is the period from 2010 to 2014, when around 3,000 to 3,500 SIs were produced annually. The devolved legislatures typically produce between 200 and 400 SIs every year.

Source: legislation.gov.uk. Note: Northern Ireland data from earlier years has not been included due to data quality issues.

Private members’ bills

Private members’ bills are public bills introduced by MPs and Lords who are not government ministers.

Private members’ bills can be introduced in the House of Commons through three different routes:

• As a ballot bill, where MPs enter their names in a ballot at the beginning of a parliamentary session. The names of 20 MPs are drawn, and the ballot decides the order in which MPs’ can choose a slot for second reading of their bill.
• As a ten-minute rule bill, where MPs can make a 10-minute speech before introducing their bill. It is possible for another MP to oppose the introduction of such a bill, and occasionally the House does not allow the proposed bill to be introduced.
• As a presentation bill, where MPs introduce a bill but cannot make a speech.

Private members’ bills can also be introduced in the House of Lords. This is usually done through a ballot.

The graph below shows the number of private members bills introduced through the routes outlined above since the 2006-07 session. The number of private members bills’ introduced in each session has increased (particularly presentation bills and ten-minute rule bills).

Source: legislation.gov.uk

In the House of Commons, a maximum of 20 ballot bills can be introduced during each session. The number of other kinds of private members bills introduced will depend on the length of the session.

The graph below shows the number of non-ballot bills introduced per sitting day. The average frequency of private members’ presentation bills has increased from around one every eight sitting days in the 2006-07 and 2008-09 sessions, to more than one per day in the 2023-24 session.

Sources: legislation.gov.uk; Number of sitting days in the House of Commons by session since 1900. Note: the 2019 session is excluded to improve the readability of other data. In that session, 2.67 private members bills were introduced in the Lords per day, and no others.

Private members’ bills rarely become law. Across all the bills introduced in the figures above:

• 34.0% of ballot bills were successful
• 1.8% of presentation bills were successful
• 1.5% of Lords private members’ bills were successful
• 0.5% of ten minute rule bills were successful

For more information, see the Commons Library briefing Successful Private Members’ Bills since 1983.

Further resources

The Commons Library briefing Acts and Statutory Instruments: the volume of UK legislation 1850 to 2019 provides further data and covers a longer historic period.

The Commons Library briefing Private Members’ Bills provides further information on private members’ bills.

For more information on legislation, visit legislation.gov.uk.

For more information on bills, visit bills.parliament.uk.