>>/50690/
That won't help.
Birth rates are rapidly declining with the advent of urbanization and increased education. In any country that is developing.
But they will definitely pass a law against childfree, because the mechanism is already running. They will pass similar laws every year (every few months), against LGBT, childfree, foreign words, spirituality, bad movies, wrong art, wrong clothes, against everything. Because you can only disable this machine by destroying it.
So yes. This law will not help with fertility, but they will accept it.
In what form?
I guess it's the usual fine for families without children. Yes, for families (with a formal marriage). Ordinary loners to fine it's fucked up, you just overload the courts and no one will ever take out such a volume of work.
They say that 12 months after marriage, you must provide a child. If not, fine.