You don't seem to understand the difference between criminal and civil law.
Criminal statutes establish some conduct as illegal (theft, rape, murder, etc.), and commission of such offenses will cause the state to act against you.
Civil law establishes rules under which individual parties may sue each other for relief, damages, etc. Libel is a civil infraction. If you write something that is maliciously untruthful about another person (and though it creeps me right the fuck out, businesses *are* legally considered persons for these purposes) and it damages them in some way, they have standing to sue you in court.
In short, the state is not telling you that you are subject to criminal prosecution for lying, but the law does allow for anyone who you lie about to sue the pants off you.