An Act of Parliament is a piece of primary legislation which has been passed by the UK Parliament. Draft Bills are debated, amended and voted on by both Houses of Parliament. If approved, they go to the monarch to receive royal assent, after which they become part of statutory law.

While Parliament represents all the constituent nations in the UK, due to devolution, most of the Acts it now passes either apply only to England and Wales, or to the UK as a whole in the case of constitutional or reserved matters. The devolved legislatures handle the majority of local policy matters.

Due to the principle of parliamentary sovereignty, Acts of Parliament are considered the supreme law of the land and cannot be challenged in court.

How an Act becomes law

An Act of Parliament will begin life as a Bill (a draft Act) which is introduced in either the House of Commons or the House of Lords and is then debated, amended, and voted on. All Bills are drafted by lawyers working for the Office of the Parliamentary Counsel.

These are the stages for Bills which begin in the House of Commons:

First reading

During the first reading, the short title of the Bill is read out in Parliament.

Second reading

The second reading consists of a debate on the general principles behind the Bill. Once finished, the House votes on whether the Bill should move to the next stage

Committee stage

During the committee stage, a committee of MPs scrutinise the drafting of the Bill line-by-line, and suggest amendments.

Report stage

The report stage consists of further debate about the Bill along with any amendments proposed during the committee stage. MPs also get the chance to suggest amendments of their own.

Third reading and vote

The Bill is debated for a final time and then voted on.

House of Lords

Once the Bill’s been through these stages, it will go to the House of Lords and begin a similar cycle from the beginning. The House of Lords may suggest further amendments and may even reject the Bill, in which case it will be sent back to the Commons again.

The Parliament Acts of 1911 and 1949 limit the power of the House of Lords to veto and delay legislation, meaning that the House of Commons can override the House of Lords after they’ve rejected it once.

Royal assent

If the Bill is successfully passed by both Houses (or the House of Commons alone if the Parliament Acts are invoked), it will be sent to the monarch to receive royal assent. Once assent is given, it will become an Act of Parliament, and therefore law.

Types of Acts

Acts of Parliament generally fall into one of three categories depending on their scope:


Acts passed in 1963 or later

Acts which were passed in 1963 or later are cited by their short title, the year they received royal assent, and their chapter number (abbreviated as ‘c’).

For example:

Short titleYearChapter
Human Rights Act1998c. 42
Coronavirus Act2020c. 7

The first Act which receives royal assent in a year is chapter 1, and the second chapter 2, and so on. So the Human Rights Act 1998 was the 42nd Act to receive royal assent in 1998, and the Coronavirus Act 2020 was the 7th Act to receive royal assent in 2020.

Acts passed before 1963

Acts passed before 1963 are cited by their short title, the year they received royal assent, the parliamentary session (as measured in regnal years), the monarch, and the chapter number.

For example:

Short titleYearRegnal yearMonarchChapter
Crown Debts Act180141Geo 3c. 90
Official Secrets Act19111 & 2Geo 5c.28

Both parliamentary sessions (which begin and end in the spring) and regnal years (which begin and end on the date the monarch came to the throne) can span across two calendar years, so this is why two numbers are sometimes given.

In the example above, the Official Secrets Act 1911 was passed during the parliamentary session which spanned across King George V’s (abbreviated to ‘Geo 5’) first and second regnal years (‘1 & 2’).

Short title

Short titles are a relatively recent development, and are what is most commonly used to refer to Acts of Parliament today. The short title usually appears on the first page of an Act.

The definite article is not usually included in the short title, but it should be used when introducing an Act in a sentence. For example, ‘the Human Rights Act 1998’ in a sentence, but just ‘Human Rights Act 1998’ in a list.

After the introduction of the short title, legislation was passed to designate short titles to Acts which were passed beforehand (e.g. the Bill of Rights 1689).

Long title

The long title describes what the Act is supposed to achieve – some can be quite detailed and specific, but others may only be brief and general. They always begin with the words ‘An Act to…’

For example, the long title for the Human Rights Act 1998 says:

An Act to give further effect to rights and freedoms guaranteed under the European Convention on Human Rights; to make provision with respect to holders of certain judicial offices who become judges of the European Court of Human Rights; and for connected purposes.

Human Rights Act 1998 c. 42

The long title is important as an Act of Parliament cannot be amended to exceed the purpose stated within its long title. For this reason, the long titles for modern Acts tend to be more general, often ending with the phrase ‘and for connected purposes’.

Chapter number

The chapter number dates back to when Acts of Parliament were printed on rolls, with each of the Acts divided into chapters.

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