I object! (your honor).

Laughter , and indeed anything even approaching a smile, needs to be severely punished.
Personally, I think any signs of mirth needs to be a sliding scale of punishment.

Obviously, this is just an outline, but something like:
Smiling more than once day in a full week period - Pull a finger nail out.
Chuckling - Cut a finger off (after pulling the nail out, obviously.

Anything more than a chuckle is the death penalty, with the strength of the laughter deciding on the the type of death.
Hung, drawn and quartering for hysterical ,peeing yourself, laughter all the way down to a simple bullet for a gentle guffaw.

I was also thinking that we need the same kind of rules for intelligence as well, but with the tight correlation between sense of humor, laughter, and intelligence, it already seems to be covered...