Intrinsic and Extrinsic Aids to Statutory Interpretation

Intrinsic and extrinsic aids are sources that help a court work out the meaning of an Act of Parliament. Intrinsic aids are found within the Act itself; extrinsic aids come from outside it. Courts use them when interpreting statutory wording, particularly where its meaning is unclear.

Intrinsic aids

An Act may contain a definitions section that explains how particular words are used. Its long title states its overall purpose, while headings and schedules can provide further context. A schedule is additional material attached to an Act and may contain detailed rules.

For example, suppose a fictional Act says, “No vehicles may enter the garden,” and its definitions section says that “vehicle” includes bicycles. The definition is an intrinsic aid: it makes clear that the prohibition covers bicycles, even if someone would not ordinarily think of a bicycle when they hear “vehicle.”

Extrinsic aids

Extrinsic aids include dictionaries, reports produced before an Act was passed, and Hansard, the official record of parliamentary debates. They can help explain the ordinary meaning of a word or the problem Parliament was trying to address. Explanatory Notes are also extrinsic: they accompany an Act but are not part of its text.

A court cannot simply use any parliamentary comment to replace the wording of an Act. Under Pepper v Hart, reference to Hansard is permitted in limited circumstances, including where the wording is ambiguous or obscure, or its literal meaning leads to an absurdity, and the relevant statement by a minister or promoter of the Bill is clear.

Exam mistake to avoid: do not describe Explanatory Notes as intrinsic just because they are published alongside an Act. The key question is whether the aid is part of the Act itself.