A more thorough explanation:

The mischief rule is a way of interpreting laws. It means that when judges are trying to understand what a law means, they should first figure out what problem the law was trying to solve. Then, they should interpret the law in a way that solves that problem.

For example, let's say there is a law that says "No dogs allowed in the park." If someone brings their dog to the park and gets in trouble, a judge using the mischief rule would try to figure out why the law was made. Maybe the problem was that dogs were leaving a lot of poop in the park and people were stepping in it. In that case, the judge might interpret the law to mean "No dogs allowed in the park unless they are on a leash and their owner cleans up after them." That way, the problem of poop in the park is solved, but people can still bring their dogs if they follow the rules.

The mischief rule is one of several ways that judges can interpret laws. Other methods include the plain-meaning rule (which means interpreting the law based on the words used), the golden rule (which means interpreting the law in a way that makes the most sense), and the equity-of-the-statute rule (which means interpreting the law in a way that is fair to everyone).