Legislative definitions 

Much of the work in reading a statute is done by its definitions. A provision that looks clear in ordinary English may mean something quite different once the defined terms are substituted, and a great many interpretation disputes are resolved without ever reaching the general principles of construction — because the Act said what the word meant.

Where definitions live

• In the provision itself, often introduced by "in this section".
• In a definitions or dictionary section, commonly near the start or in a schedule. Read it before the operative provisions, not after.
• In an Interpretation Act, which supplies default meanings for terms used across the statute book of that jurisdiction — words such as "person", "document", "month" and "may". Each jurisdiction has its own, so identify the right one: for Commonwealth Acts it is the Acts Interpretation Act 1901, which also supplies the purposive rule against which a definition is read.²
• By incorporation from another Act, which the provision will state expressly.

A defined term is conventionally signalled by a capital or by the phrase "as defined", but neither is universal. If a term is doing real work in a provision, check whether it is defined before assuming its ordinary meaning.

How definitions operate

• Exhaustive definitions use "means". They replace the ordinary meaning entirely.
• Inclusive definitions use "includes". They extend the ordinary meaning rather than displacing it, so the term retains its ordinary sense plus what is listed.
• Mixed forms — "means … and includes …" — are common and should be read carefully: the "means" limb is closed, the "includes" limb extends it.
• Deeming provisions treat something as being what it is not, and their scope is limited to the purpose for which they deem.

The distinction between "means" and "includes" is one of the highest-value habits a student can build. Arguments are regularly won on it.

Definitions have boundaries

A definition applies only where the Act says it does — "in this Act", "in this Part", "in this section". Applying a Part-limited definition to the whole Act is a common error.

Definitions are also subject to contrary intention: most Acts and Interpretation Acts provide that a definition applies unless the contrary intention appears, so context can displace it.

Definitions and the general principles

Definitions do not sit outside the ordinary approach to construction. They are read in context and consistently with the purpose of the Act, per CIC Insurance Ltd v Bankstown Football Club Ltd (1997) 187 CLR 384,¹ and a definition that produces an absurd or incoherent result in a particular provision may be read down. But the starting point is the text the legislature enacted, and a defined term is that text.

Applying this in a problem question

1. Identify every term in the provision that might be defined.
2. Locate the definition and note its scope — Act, Part or section.
3. Determine whether it is exhaustive or inclusive, and say which.
4. Substitute the definition into the provision and read the result.
5. Check the jurisdiction's Interpretation Act for any term still undefined.
6. Consider whether context discloses a contrary intention.

Where the authority sits

The definitions themselves are legislation — cite the Act, the section and the jurisdiction. The Interpretation Act of the relevant jurisdiction supplies the defaults, and general principles of construction come from case law.