People use extremes of physical punishment to justify reasons why corporal punishment should not be used. But extreme's are rare and legislating against it doesn't stop abuse.
As in all things common sense should prevail. I understand many of the references 10ClarionSt has used and would agree, in the main, that such mild physical chastisement as a clip around the ear have little long term effect on children. But I do find myself concerned at reference to a leather belt.
In my opinion the answer is 'it depends'. I used 'corporal punishment on my children when they were small but only in certain circumstances. The 'naughty step' hadn't been invented and people weren't exposed to so much 'advice' or 'learned opinion' as they are now so sometimes, when telling hadn't worked, when repeated threatening didn't work then yes - I smacked them. Most of the time this happened it was because they were about to do something which would have hurt them a lot more than the smack did. Once they got to the stage where communicating with them was really possible and they really began to understand the implications of their behaviour ( 7 or 8) it became unnecessary and I can't recall a time after that when they were smacked.
I don't agree with formal corporal punishment at school - although I must admit I feel there would be fewer problems if teachers were able to administer a 'clip around the ear' at times.