Mischief Rule :Observations of Irish Law Reform Commission

The mischief rule, the oldest of the rules of interpretation, reflects a balance of the legislative and judicial powers which some consider renders it inapplicable today. It presumes a legal system in which legislative intervention in the common law is an exceptional occurrence, used only to address a "mischief" or "defect" in the common law. Though it may be expressed in outdated terms, however, the rule bears similarities to the purposive and schematic approaches to interpretation which have been developed by modern day courts. The mischief rule has been given legislative force in a number of common law jurisdictions and is still cited by the courts. The rule was recently referred to in the Irish High Court, where Budd J identified the need to examine "the mischief sought to be addressed by the passing of An Blascaod Mór National Historic Park Act, 1989 ."

The mischief rule was set out in Heydon's case, where it was held that four matters might be considered in the interpretation of statutes :
1. "What was the common law before the making of an Act;

2. What was the mischief and defect for which the common law did not provide;

3. What was the remedy the parliament hath resolved and appointed to cure the disease of the commonwealth;

4. The true reason of the remedy.

And then the office of all the judges is always to make such construction as shall suppress the mischief, and advance the remedy and to suppress subtle inventions and evasions for continuance of the mischief, and pro privato commodo , and to add force and life to the cure and remedy, according to the true intent of the makers of the Act, pro bono publico .

Statutory Drafting and Interpretation, Consultation Paper on: Plain Language and the Law (LRC CP14-1999) [1999] IELRC 1 (1st July, 1999)

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