This week has been filled with reports about NFL Minnesota Vikings running back Adrian Peterson’s accusation of reckless or negligent injury to his four-year-old son. The incident has once again raised the controversy surrounding the use of corporal punishment.

Three issues are key in this debate:

1) What is spanking? People have wide variations in their definitions when it comes to actually defining spanking. According to Webster, spanking is “to strike especially on the buttocks with an open hand.” The American Academy of Pediatrics adds that the strike should not cause physical injury of any kind. When physical injury occurs, the spanking moves from discipline to abuse. In Peterson’s case, the pictures tell a story of injury to the child and the child was not spanked with an open hand.

2) Is spanking effective? Spankings stops a behavior. Children comply immediately, but it does not improve behavior. One study of moms who spanked their children showed that within 10 minutes, 73% of the children spanked were again engaging in the same behavior. Other studies show that spanking can be effective in the short-term for children ages 2-6 when used with other mild disciplinary methods like reasoning and time-out. In the long-run, however, when spanking is continuously used, there is an association with depression, aggressiveness and antisocial behaviors. This doesn’t mean that spanking causes those behaviors, only that it is associated with those behaviors. It may be that difficult kids are more prone to those behaviors anyway.

3) What does spanking do to the relationship between parent and child? Certainly spanking models physical aggression as a way to deal with behavior. It is also associated with poorer relationships between parents and children. The problem is that spanking can easily escalate to a parent being out of control and becoming overly aggressive. This is especially true when you use an object other than your hand because you can’t easily monitor how hard you are hitting the child. Frequency and severity of corporal punishment matter. In Peterson’s case, the photos of the child may indicate that he crossed a line. And if he did, the relationship suffers.

Bottom line: There is a difference between controlled spanking and child abuse. This is one of the reasons many schools still allow spanking and why it is legal in all states. The problem comes when spanking becomes frequent and severe causing injury to the child. That is when cases are reported to be investigated for abuse.