[fastball]

Literally all of the things you mentioned except Child Pornography (which is more of a production issue than speech issue anyway) meet that standard. So we can clearly write laws about it. No, lying in general isn't limited. Lying that damages other people/things is, however.

It's only perjury if you knowingly lie, which (when under oath) damages the integrity of the justice system. It's only libel if you tell a deliberate falsehood and it damages someone else directly. etc.