In many countries, a statutory instrument is a form of delegated legislation.
Statutory instruments (or 'regulations') are primarily governed by the Statutory Instruments Act 1946, which replaced the system of statutory rules and orders governed by the Rules Publication Act 1893.
Following the 2016 EU membership referendum and the subsequent publication of the European Union (Withdrawal) Bill, there has been concern that its powers enabling ministers to issue statutory instruments under the bill may enable the government to bypass Parliament. Although this has been criticised by some as being undemocratic, draft regulations must be "laid before" Parliament, which may always demand a full debate on contentious issues.
Devolved administrations also have the power to make Statutory Instruments within the heads of powers that are devolved to them.
Wales Statutory Instruments made by the Welsh Government are published as a subseries of the UK statutory instrument series—for example, the Environment (Wales) Act 2016 (Commencement No. 3) Order 2017 is numbered 2017 No. 714 (W. 171), meaning it is the 714th statutory instrument in the UK series and 171st in the Wales subseries.
In Scotland, statutory instruments made by the Scottish Government were governed by the Statutory Instruments Act 1946 following devolution until the Interpretation and Legislative Reform (Scotland) Act 2010 came into force. Unlike Wales Statutory Instruments, Scottish Statutory Instruments are not published as a subseries of the UK series—instead, they are published separately by the Queen's Printer for Scotland. However, any UK statutory instruments dealing with reserved matters and applying only to Scotland are published in a UK subseries, such as the Insolvent Companies (Reports on Conduct of Directors) (Scotland) Rules 2016 numbered 2016 No. 185 (S. 1).: 12 
In the Republic of Ireland the term "statutory instrument" is given a much broader meaning than under the UK legislation. Under the Statutory Instruments Act 1947 a statutory instrument is defined as being "an order, regulation, rule, scheme or bye-law made in exercise of a power conferred by statute".
However, only certain statutory instrument are published and numbered by the Stationery Office, this being mostly where the statute enabling the enactment of delegated legislation required that any such legislation be laid before the Houses of the Oireachtas.
Two close equivalents of similar operation are
Canada uses statutory instruments for proclamations by the Queen of Canada. For example, the Proclamation of the Queen of Canada on April 17, 1982 brought into force the Constitution Act 1982, the UK parts of which are known as the Canada Act 1982.