[acallan]

> What about slander and libel laws or laws about claims made in advertisements?

Yep — here we're getting into Prior Restraint. It's both against the law to restrain free speech such as lies, but as you rightly point out, this speech can have other legal consequences.

[Eddy_Viscosity2]

Well there we go, an established framework for how this could work. Legal consequences are good enough.