Quote Originally Posted by LittleGrizzly
...whereas a case like this is the goverment making a consequence from an action that previously had no punishment.
Copulation between non-married people has always been illegal in the US, with punishments varying state-by-state, and (of course) enforcement also varying over time and cultural tolerance.

The laws against consenting adult copulation have gradually relaxed, and are almost non-existent now. But the laws about "childhood" copulation, as we see in this case, persist, and in some places, are on the rise.