A more thorough explanation:

Definition: Mala prohibita refers to an act that is considered a crime only because it is prohibited by law, even if the act itself is not necessarily immoral. Examples of mala prohibita include minor offenses such as jaywalking or running a stoplight, as well as many regulatory violations.

Unlike malum in se, which refers to acts that are inherently immoral and universally recognized as such, mala prohibita offenses are only considered wrong because they are against the law. This means that an act can be mala in se even if it is not punishable by law, and that an act can be malum prohibitum even if it is not inherently immoral.

For example, stealing is considered malum in se because it is universally recognized as wrong, regardless of whether or not it is against the law. On the other hand, selling alcohol to minors is considered malum prohibitum because it is only wrong because it is against the law, not because it is inherently immoral.