Some even perform sacrifices on infant children that noone else knows were born. Just because the government will not be able to enforce the law perfectly is not a reason to have no law (nor is it a reason to have a police state to attempt perfect enforcement). There will be women who murder their unborn babies and get away with it, which you euphemistically refer to as "self-induced abortion", but IMHO it ought to be illegal just like rape, other types of murder, theft etc. The point is that the logic of "people are just going to do it anyway" isn't sound because it would imply that there should be no law at all about anything. The reason I believe drugs and alchohol should be legal is because I believe people have rights under natural law to choose what to put in their body so long as they do not harm others; that a dangerous black market is created by prohibition of certain substances is beside the point. There is a dangerous black market in the murder for hire business for example, but that does not imply that hitmen should be regulated and taxed.