The purposive approach (sometimes referred to as purposivism,purposive construction,purposive interpretation, or the "modern principle in construction") is an approach to statutory and constitutional interpretation under which common law courts interpret an enactment (i.e., a statute, part of a statute, or a clause of a constitution) within the context of the law's purpose.
Purposive interpretation is a derivation of mischief rule set in Heydon's Case, and intended to replace the mischief rule, the plain meaning rule and the golden rule. Purposive interpretation is used when the courts use extraneous materials from the pre-enactment phase of legislation, including early drafts, hansards, committee reports, and white papers. The purposive interpretation involves a rejection of the exclusionary rule.
Israeli jurist Aharon Barak views purposive interpretation as a legal construction that combines elements of the subjective and objective. Barak states that the subjective elements include the intention of the author of the text, whereas the objective elements include the intent of the reasonable author and the legal system’s fundamental values.
Critics of purposivism argue it fails to separate the powers between the legislator and the judiciary, since it allows more freedom in interpretation by way of extraneous materials in interpreting the law.
The plain meaning rule gained popularity during the 18th and 19th centuries as the courts took an increasingly strict view of the words within statutes. Under the plain meaning rule, the words of the statute are given their natural or ordinary meaning. The plain meaning rule of statutory interpretation should be the first rule applied by judges.
One of the leading statements of the plain meaning rule was made by Chief Justice Nicholas Conyngham Tindal in the Sussex Peerage (1844)