A new Australian series called "The Slap" has resurrected the debate over "smacking." Christopher Wakling remembers losing it with his son (he's since written a novel on the subject):
I’d smacked my son for a reason. I’d tried every other non-violent means of discipline. I’d shut him in his room, and plonked him on that damn step. Perhaps more damagingly, I’d bellowed at him. Nothing worked. The smack cut straight to the point. Don’t do that again, it said. And he didn’t. But to see my son flinch from me made me feel physically sick.
Some legal background here. When "smacking" takes an ugly turn here, here and here.
The Dish 