In a nutshell, administrative law is about challenging official power.
Challenge can be by an individual, company or non-profit organisation.
Primarily an area of public law that regulates the relationship between the executive government and those it governs. This is to make that administrative body acts within the law.
End of the 19th Century Professor Dicey, an influential figure in English constitutional law, denied the very existence of a separate branch of administrative law. Claimed that administrators were subject to the same “rule of law as individuals and were liable for any illegal or arbitrary action in the ordinary courts of law.
Values or public policy principles should underpin administrative law. A semi-official view, the Administrative Review Council (ARC) has identified five core values of the Commonwealth administrative system, namely, lawfulness, fairness, rationality, openness (or transparency) and efficiency.
Help understanding Administrative Law it is helpful to look at leading cases. An example may be the Haneef Case
This case demonstrates how administrative law can be used to constrain executive power.
90% of Administrative Law consists of statutory interpretation.
Haneef was initially detained for nearly two weeks without charge under the provisions of the counter-terrorism legislation adopted since 2002.
Immigration minister Kevin Andrews revoked Dr Haneef’s visa just after a magistrate had granted Haneef bail on a charge of providing support to a terror organisation, while “reckless” as to whether a terrorist organisation was involved.
Here, we are concerned with this ministerial power, not the criminal charges against Haneef, which were later dropped.
The minister’s visa cancellation was a matter of administrative law.
Minister Andrew’s exercised a personal discretion vested in him by S 501 of the Migration Act 1958 (Cth) to cancel a visa if he considered a person failed the “character test” Andrews said Haneef had an “association” with two second cousins, living in Britain, who has been accused of involvement in two bombing attempts.
Attorney-General Phillip Ruddock then issued a Criminal Justice Certificate under s 145 of the Migration Act.
Haneef would be held in immigration detention pending trial, rather than being released on bail.
Visa decision was then challenged
Minister was adamant on the visa cancellation relying on the S 501 that Haneef provided a “significant risk” that a person would “incite discord in the Australian community” or “become involved in activities that are disruptive” to that community.
Spender J held that the wrong interpretation of the word association is a jurisdictional error and quashed the cancellation of the visa. Thus disposing the case. He also talked about how if associations made with family members were to be relied on, then almost anyone can be held to have their visa cancelled, many people are descendants from convicts was the example.

New Administrative law
Steps by courts themselves to extend and somewhat regularise their powers of judicial review, sometimes dismantling previous narrow restrictions (for example, broadening the scope of procedural fairness and jurisdiction error).
Legislation at both federal and state levels to codify, simplify and sometimes extend the scope of judicial review
Federal and state legislation to introduce non-judicial forms of review including administrative tribunals, Ombudsmen, anti-corruption bodies, such as the NSW Independent Commission against Corruption (ICAC) and freedom of information (FOI) provisions.
Establishment of the ARC, conducts regular structural review of the federal administrative law system as a whole.

Five major factors could be said to have led to the modification
Development and extension of the post-world was 2 welfare state, encompassing, for example, the provision of social security benefits to single parents and students
Rising demand for greater recognition of social security and other