If masturbation in the USA suddenly became illegal and was punishable by death...

Insert gif of Matthew McConaughey thumping his chest

 

A decent psychological study could assess males' likelihood of marriage or serial dating based on demographics, appearance and emotional intelligence, and then with each tier of risk of bachelorhood affix a more stringent preventive measure: estrogen therapy, reversible vasectomy, medical castration and straight testectomy. Obesity and alcoholism would skyrocket; rape would clearly decline but be replaced five-for-one with straight physical assault. The birth rate would decline, but parenthood would have social currency and individual couples or females would have more kids per capita.

I think the old anti-sodomy laws are probably the closest we've come to this. I think those were hard to arrest or prosecute on unless people were being ratted out by neighbors or meeting up in some public place to do it. If you're doing periodic or random fap checks of some kind, female cops are probably in higher demand.