A more thorough explanation:

The purpose approach, also known as the mischief rule, is a doctrine used in statutory construction. It states that a statute should be interpreted by first identifying the problem or "mischief" that the statute was designed to remedy. Then, a construction should be adopted that will suppress the problem and advance the remedy.

For example, let's say there is a law that prohibits the sale of alcohol to minors. The purpose of this law is to prevent underage drinking and its negative consequences. If a new type of alcoholic beverage is created that is not explicitly mentioned in the law, the purpose approach would be used to determine whether the sale of this new beverage to minors is prohibited or not. The court would look at the purpose of the law and determine whether the sale of this new beverage would advance or suppress the problem of underage drinking.

Another example is a law that requires all drivers to wear seat belts. The purpose of this law is to increase safety and reduce injuries in car accidents. If a person is pulled over for not wearing a seat belt but claims they were only driving a short distance, the purpose approach would be used to determine whether the person violated the law or not. The court would look at the purpose of the law and determine whether the person's actions advanced or suppressed the problem of car accident injuries.

These examples illustrate how the purpose approach is used to interpret laws based on their intended purpose and the problems they were designed to solve.