Under the common law (and prior to 1975 reforms) there was no general right to obtain reasons for a government department's decision. Sometimes, if clear reasons are obtained, errors in the decision can be found. It can then be decided whether a challenge is possible and if it is likely to be successful. Reasons may also explain to a person affected by the decision why it was the correct decision.

It is generally regarded as an important (although not always essential) first step to obtain the reasons for any decision. This is not always easy in situations where many standard notices are generated by computer programs.

The first stage of attempting to find the reasons is to discuss your request with the relevant government body. This may include the officer who made a decision (such as the Authorised Review Officer named in a Social Security decision) or the officer who signed the letter advising you of a decision. If this fails a request for copies of the records may be made using Freedom of Information legislation, see freedom of information. Where the reasons are inadequate or difficult to understand, the official record or any official correspondence may be very informative and this may assist in deciding whether judicial review is worthwhile.

It may be necessary to issue legal proceedings to obtain more information from the administrative body about its actions - for example, by seeking an order for the discovery of documents (that is, obtaining access to the government's file and other relevant documents). These steps may be answered by the government with a claim that the documents are subject to Crown privilege (that is, to reveal documents in its possession would irreparably harm the community's interests). This claim is subject to court scrutiny and courts in recent years have shown increasing reluctance to uphold such claims by government. However, discovery procedures and claims of Crown privilege can be slow and time consuming.

Not being able to obtain reasons may constitute a basis for a complaint to the Ombudsman, who may determine that it is fair in all the circumstances that reasons should be given.

There are also a number of areas where there is a statutory obligation to provide reasons for decisions. Many Acts of Parliament (primarily Commonwealth, but increasingly also State Acts) now require that reasons for decisions be provided. This obligation will of course only apply to the specific decision covered by the Act.

There are also general powers to obtain reasons for decisions. In the Commonwealth sphere, the most common of these is under the Administrative Decisions (Judicial Review) Act 1977 (Cth) [s.13]. Not only is there an enforceable right to obtain reasons for a decision, but those reasons for the decision then constitute the basis upon which a review application can be argued.

There are several limitations on the obligation to supply reasons [s.13A]. A statement of reasons may omit information relating to the personal or business affairs of a person (other than the person making the request) where it is information:

Where such an omission occurs, a reason must be given [s.14]. In addition, the Attorney-General may give a certificate stating that certain matters cannot be disclosed as they are contrary to the public interest where:

Where information is omitted, a reason must also be given.

There is no equivalent general right to obtain reasons for decisions in the State sphere. Individual Acts dealing with specific decisions may give a person a right to obtain reasons for a decision.