The problem lies in how such a law can be used; unless the law is weak it will likely be abused (but then its effectiveness will also be minimal).
If somebody has a track record of lying, it should be easier to prove subsequent lying.
Of course, then the potential for abuse is greater. It's about finding the right balance.
The problem lies in how such a law can be used; unless the law is weak it will likely be abused (but then its effectiveness will also be minimal).