The issue is who decides what is false. Will people be prosecuted for saying true things that the state says is false? It's not like the state would lie about something.
You're referencing defamation law and contract law. In the case of defamation, you can't be defamed if what the person said is true. And in case of contract law or fraud, lies impact the integrity of a transaction.
In the US, you can lie as much as you want with general speech.
> You’re referencing defamation law and contract law.
Why do you think this? The WP article is about a general exception to the constitutional right to freedom of speech, though it is not absolute. It happens to mention some defamation and contract precedent, but if you read it, it’s quite clear the exception is broader than those two cases and not limited to defamation and contracts. It even gives several other categorical examples (such as incitement and slander), so you seem to have gotten the wrong idea.
> In the US, you can lie as much as you want with general speech.
As a summary of the issue, this is mostly false and rather misleading. It’s certainly bad advice in any case. ;) You can choose to lie a lot and you might not get in trouble, but if you knowingly lie about things that materially affect other people, you’re probably not protected in the free speech sense. However the only way to be sure is to go to court, and most people who lie don’t end up in court.
Good grief. I linked to an article describing the exception and the exceptions to the exception. This exception to free speech is widely titled, cited, and summarized as the “false statements of fact exception” to free speech. It’s a name, not a complete description, which is why I provided one version of a complete description that has links to all sources.