Contraception encourages promiscuity ... is an oft-repeated argument. I've sometimes wondered why this counts as an argument againstcontraception but ho hum when I hear it I am reminded of Gulag Archipelago in which Solzenitzen relates how one camp had the mens and womens compounds next to each other. They were separated by razor-wire and a dog run and yet the zeks still managed to get some illicit nookie in. The woman would back-up against the wire while the man braved the dogs.
Considering that dogs, guns, and sharp wire were not enough to keep people apart, what chance has mere laws?
Personally I'd encourage safer sex. The more the merrier. There are so many other things sexually frustrated people could be getting up to that are much more destructive. Let's return to the free love ethos - now without the disease risks.