I wouldn't presume to tell you how to bring up your children...I simply have never needed to smack in order to instill discipline or fear of danger. I just disagee that its needed, rather than making a specific judgement about smacking overall. I certainly do not think that smacking should be banned or a matter for the state to regulate.....of course it is all about scale however.
Like Dimple says, he has one daughter where smacking wasn't necessary and another where it was, so for him in his situation maybe, I cannot judge another on something I have not witnessed....I can only go by my own experience which if i am being objective is biased due to my extremely abusive and violent childhood so I am triplely aware of what violence can do to a child. That is not to equate what I went through with a light smack however, I would just be very careful about how and when to use such a technique and always find an alternative....it would be a last resort for me, luckily I have never felt it necessary.