The rule was illustrated in the case of Smith v Hughes  2 All E.R. 859, where under the Street Offences Act 1959, it was a crime for prostitutes to "loiter or solicit in the street for the purposes of prostitution". The defendants were calling to men in the street from balconies and tapping on windows. They claimed they were not guilty as they were not in the "street." The judge applied the mischief rule to come to the conclusion that they were guilty as the intention of the Act was to cover the mischief of harassment from prostitutes.
meaning rule, in that it can only be used to interpret a statute and, strictly speaking, only when the statute was passed to remedy a defect in the common law.
as opposed to the Golden or Literal rules.
It would be interesting to quote the observations of Professor Cote on the difference of approach between the literal and Mischief Rules.