A more thorough explanation:

The single-subject rule is a principle that states that a law should only address one topic, which must be clearly stated in its title. This rule is also known as the one-subject rule.

For example, a law titled "An Act to Regulate Traffic and Increase Penalties for DUI Offenses" would violate the single-subject rule if it also included provisions for regulating gun ownership. However, a law titled "An Act to Regulate Traffic" would be in compliance with the single-subject rule.

The purpose of the single-subject rule is to prevent lawmakers from sneaking unrelated provisions into a bill in order to pass them without proper scrutiny. By requiring that each law address only one topic, the rule ensures that lawmakers and the public can fully understand and debate the implications of each law.