When my wife and I were going through training to be foster parents, the issue of spanking was discussed numerous times. At least in my state, Tennessee, foster parents may NOT use corporal punishment in any form. Now Tennessee does not have any restriction on parents using on their own kids but not on foster kids. The reason, and I think it is a good one, is that most kids placed into foster care have been physically abused at some point or another. For some it might trigger flashbacks, for others it will simply be of nil effect (in short that kid thinks, "yeah, go ahead spank me, my old man hit me harder than that").
We came up with some creative ways to punish disobedience. The 13 year old boy we had was quite popular with the girls at school and like to smell good for them. When he acted up one time, we took away his good smelling deodorant and body wash, and gave him plain generic unscented stuff.
I think he would have rather we spanked him.
Never acted up again.
All this being said, I think there are times when willful defiance and disobedience calls for spanking. It really depends on the kid's temperment and attitude as well as the situation. There are some kids that temperment wise should never be (nor would likely need to be) spanked. But there are some that might need that on occasion.