(Separated from my other reply because it's a sparate point.)

Personally, I strongly doubt the incidence of infanticide-inspired sadism would be sufficiently higher in a culture in which infanticide were legal to justify keeping it illegal in this culture.

And I don't want to live in a society which views the killing of babies as good, or which values people less. I just don't want it to be illegal. I don't want to live in a society which encourages suicide, either, but I do think it ought to be legal.