In parliamentary systems and presidential systems of government, primary legislation and secondary legislation, the latter also called delegated legislation or subordinate legislation,[1] are two forms of law, created respectively by the legislative and executive branches of government.  Primary legislation generally consists of statutes, also known as 'acts', that set out broad outlines and principles, but delegate specific authority to an executive branch to make more specific laws under the aegis of the principal act.  The executive branch can then issue secondary legislation (mainly via its regulatory agencies), creating legally-enforceable regulations and the procedures for implementing them. [ 2]

Church of England Measures – the instruments by which changes are made to legislation relating to the administration and organisation of the Church (UK only). 

'primary legislation' means any—

(a) public general Act;

(b) local and personal Act;

(c) private Act;

(d) Measure of the Church Assembly;

(e) Measure of the General Synod of the Church of England;

(f) Order in Council—

(i) made in exercise of Her Majesty's Royal Prerogative;

(ii) made under section 38(1)(a) of the Northern Ireland Constitution Act 1973 or the corresponding provision of the Northern Ireland Act 1998; or

(iii) amending an Act of a kind mentioned in paragraph (a), (b) or (c);

and includes an order or other instrument made under primary legislation (otherwise than by the Welsh Ministers, the First Minister for Wales, the Counsel General to the Welsh Assembly Government, a member of the Scottish Executive, a Northern Ireland Minister or a Northern Ireland department) to the extent to which it operates to bring one or more provisions of that legislation into force or amends any primary legislation...

In the United Kingdom, secondary legislation (also referred to as delegated legislation or subordinate legislation) is law made by an executive authority under powers delegated from by an enactment of primary legislation, which grants the executive agency power to implement and administer the requirements of that primary legislation.[4]

Special Procedure Orders – a form of delegated legislation to which special parliamentary procedure applies.  Part of this procedure gives those people or bodies who are especially affected by the order the right to petition against it to either House. 

Hybrid instruments – statutory instruments which need to be approved by both Houses and affect some members of a group (whether individuals or bodies) more than others in the same group.[6]

'subordinate legislation' means any—

(a) Order in Council other than one—

(i) made in exercise of Her Majesty's Royal Prerogative;

(ii) made under section 38(1)(a) of the Northern Ireland Constitution Act 1973 or the corresponding provision of the Northern Ireland Act 1998; or

(iii) amending an Act of a kind mentioned in the definition of primary legislation;

(b) Act of the Scottish Parliament;

(ba) Measure of the National Assembly for Wales;

(bb) Act of the National Assembly for Wales;

(c) Act of the Parliament of Northern Ireland;

(d) Measure of the Assembly established under section 1 of the Northern Ireland Assembly Act 1973;

(e) Act of the Northern Ireland Assembly;

(f) order, rules, regulations, scheme, warrant, bylaw or other instrument made under primary legislation (except to the extent to which it operates to bring one or more provisions of that legislation into force or amends any primary legislation);

(g) order, rules, regulations, scheme, warrant, bylaw or other instrument made under legislation mentioned in paragraph (b), (c), (d) or (e) or made under an Order in Council applying only to Northern Ireland;

(h) order, rules, regulations, scheme, warrant, bylaw or other instrument made by a member of the Scottish Welsh Ministers, the First Minister for Wales, the Counsel General to the Welsh Assembly Government, a Northern Ireland Minister or a Northern Ireland department in exercise of prerogative or other executive functions of Her Majesty which are exercisable by such a person on behalf of Her Majesty;

In the United States, primary legislation is, at the federal level, an Act of Congress, and the statute that delegates authority is called an authorizing statute or delegation of rule making authority. 

A law promulgated by the executive branch agency of the United States Government as the result of primary legislation is called a regulatory law, as legislation is used only to refer to acts of the legislative branch, never the executive or the judicial branches.  The body of law that governs the agency's exercise of rule making and adjudication powers is called "administrative law," primarily the Administrative Procedure Act. 

[Legislative power] is vested exclusively in Congress [and judicial power] in the “one supreme Court” and “such inferior Courts as the Congress may from time to time ordain and establish”.... Agencies make rules... and conduct adjudications... and have done so since the beginning of the Republic.  These activities take “legislative” and “judicial” forms, but they are exercises of—indeed, under our constitutional structure they must be exercises of—the “executive Power. ”[8]

A Directive[11] is an order to Member States to pass legislation.  It is "binding as to the result to be achieved", but Member States can choose their own form of implementation.  EU citizens may have standing to pursue failures to implement, as in Francovich v Italy. 

A Decision[11] is a law that addresses a specific issue.  Addressees may challenge a decision via Judicial Review. 

The Commission may take executive action in pursuance of policy, and may even act quasi-judicially in matters of EU competition law, a power defined in Article 101 and Article 102 of the Treaty on the Functioning of the European Union.  Privileged parties, such as Member States, EU Institutions, and those with specific standing, may initiate litigation.  For example, the Commission may sue Member States for breaches of EU obligations, and Member States may sue Institutions or other Member States for breach of EU law. 

^In 2015, Italy's Constitutional Court for the first time involved itself in the core of parliamentary procedure, issuing a judgment (n. 32/2014) protecting the balance of power from the combined effects of maxi-amendments and confidence being asked of it by the government.[clarification needed][9]