That's already the law in many contexts - e.g., making a knowingly false statement to the Congress is a felony AFAIK. It's just not enforced because if it were, the Attorney General would have to put himself in jail, together with a good bunch of his peers and colleagues from other departments and agencies.
Lying under oath, a.k.a. perjury, is always unlawful. I'm speaking of when not under oath and knowingly fabricating stories or making stuff up like the reply below alludes to.
The police can lie to you but if you lie to the police you can be charged with obstruction of justice (which I believe you should be if you knowingly do it). The police and government officers and officials should be charged with obscuring the truth if and when they knowing spread falsehoods and lies. Because of the imbalance of power and consequences, it's rarely, if ever, a good idea to talk to the police (and this is a shame).
I assume he refers to the common practice of police promising leniency in exchange for cooperation, then ignoring the offer after the suspect cooperates.
Or when police lie about an accomplice having cooperated and implicating the suspect - so hey you should help us out to and save yourself.
Or when police pretend to be hitmen, seeking payment for murder. Or when police pretend to be drug dealers. Or when police pretend to be terrorists or weapons smugglers or or or or.
