It's amazing how much children can learn by talking with them, explaining consequences of behavior. It's also interesting to see a child get a swat to teach them to stop hitting. They seem to pick up quickly on what is done by reacting with impatience versus something done from a thoughtful heart, even if it is in the form of a swat.

Spanking and physical discipline are Biblical as the above post listed but also in those verses is the command to correct and teach. Just hitting a child will not help but a firm but gentle smack can and does work to get their attention, let them know who is in charge and instantly get them to stop misbehaving so you can then sit down with them and talk about the incident and why they were physically disciplined. Yes some kids will not respond well to physical discipline but others respond to little else. It is up to a parent to use wisdom on how they discipline a child and other Christians to realize that our form of discipline may not line up with another person, but we have no right to step in or judge them ("Christian commentators that advocate spanking lose credibility immediately.") unless they are harming the child in some way.

I can see that the Bible does talk about 'the rod of correction' but I believe that refers to discipline in general.
I would much prefer to discipline without physical punishment. One day my son is going to be bigger than me, and I don't want to have taught him that it's okay to pick on weaker vulnerable people.
How can we tell a child off for hitting if we spank him at home? I want to teach my son to express anger, frustration and annoyance at people without hitting out. How can I teach him if I don't model that behaviour?

The Bible is specific in giving parental advice on discipline. I understand that the Old Testament books are "under the law" and when Jesus died on the cross for our sins it cancelled "living under the law" and brought us under grace... But Proverbs is a book of wisdom and not a book of law. The book of Proverbs says the following:

Proverbs 13:24 He that spareth his rod, hateth his son. But he that loveth him chasteneth him betimes.

Proverbs 22:15 Foolishness is bound in the heart of a child but the rod of correction shall drive it far from him.

Proverbs 23:13-14 Withhold not correction from the child: for if thou beatest him with the rod, he shall not die. Thou shalt beat him with the rod and deliver his soul from hell.

Proverbs 19:15 The rod and reproof give wisdom, but a child left to himself bringeth his mother to shame.

There are times that call for spanking as a form of correction but it should not be done out of anger or with a bare hand.

Science is highly overrated - look at what it did to breastfeeding! However, "disciplining" your children physically is lazy parenting. UN involvement? Nah. But parents that slap, spank, hit usually do so reactively, out of anger. Not especially Christian behavior. It's actually rather sick. The big, trustworthy, source of all love, food, care walloping the smaller, dependent, helpless and by this time,extremely confused and distressed child.
Christian commentators that advocate spanking lose credibility immediately. I have raised two bright, happy, well-behaved, and well-adjusted children without resorting to spanking. It takes more effort. One must deny oneself occasionally to focus on them long enough to figure out what motivates them, and what non-physical punishment will get their attention. However, as gifts from Almighty God, my children are worth the effort.
So, as Christian issues go, claiming the "right to spank?" Whatever you do the least of these, you do to me.