I think children shouldn't be smacked. Ever.

It's more a matter of culture and upbringing (therefore education) than law. Even though law punishes the parent, what could punishment be, sum of money paid for smacking the kid? This of course hits the low income families, so kid is additionally being hit by poverty.

New law can be used as means to induce fear from consequences, but I doubt it leads to eliminating violence towards children in the long run. People living in fear are more reactive, therefore more likely violent.

People living in poverty (economic, emotional or mixed) are living in fear already.