Delegated or secondary legislation allows the government to make changes to a law without needing to push through a completely new act of Parliament.
This can occur when primary legislation (an act of Parliament) specifies that changes to the law may be delegated to ministers in certain circumstances in future.
Delegated legislation may allow ministers to make technical changes to the law, like altering the level of a fine, but it can also sanction broader changes like fleshing out an act with greater detail.
Its main purpose is to avoid overloading the parliamentary timetable.
Statutory Instruments (SIs) form the majority of delegated legislation, but other types include regulatory reform orders and human rights orders.
Ministers currently enact about 3,500 SIs each year.
The Delegated Powers Scrutiny Committee, established by the House of Lords in 1992, examines all Bills with delegating powers before they begin their passage through the House.
The House of Lords has also set up the Merits of Statutory Instruments Committee, which pores over the legislation resulting from delegated powers.
Finally, members from both Houses make up the Joint Committee on Statutory Instruments, which does not look at the merits of SIs but rather at how closely they comply with the provisions in the original act.