Parliament don't have time to make all law we need so allowing other body's to make it on behalf of parliament saves time and is much quicker to produce than an act
Parliament may not be suitable to make law in some cases as they don't have the relevant expertise needed so the relevant minister of department are better suited to make law in their area of responsibility due their expertise
Law is needed in local areas which parliament aren't aware of so local authorities can make these laws for the welfare of society
There are concerns over quality as it is done much quicker than parliament it could be rushed and poorly considered leading to appeals
Too much law may be made through delegated legislation making it difficult for lawyers to keep up to date
Delegated legislation can also be undemocratic as law can be made with just the authority of 1 person and controls like scrutiny committee aren't required so poor quality laws can lead to ultra vires
A form of delegated legislation made by the privy council, a body of 420 members of MPs, lords and ministers, to create law on parliament's behalf in emergencies or when parliament is on recess
Drafted by the government of the day and sent to the privy council for approval, when approved it is sent to the monarch who signs it and the law is made
Methods courts/judiciary use to control delegated legislation
Judicial review in the high court - a high court judge can consider the validity of delegated legislation
Substantive ultra vires - law is made by a minister/privy council/local authority that an act does not permit them to make
Procedural ultra vires - the correct body makes a law but doesn't follow the procedure the act said, e.g. failing to send the draft to a scrutiny committee
By-laws can be declared invalid if they break the rules of unreasonableness, e.g. bias, corruption or irrationality