Brief spankings for seriously bad behavior can be effective so long as it is clearly and calmly explained to the child afterwards why they were in trouble to begin with. Using spanking excessively or overly forcefully can actually lead to an increase in behavioral problems and damage the child's relationship with the parent forever. It's not that I'm dead-set against it, but I do think it should be used with discretion. For minor misbehavior something like a time out can work better. There are several journal articles out there on this topic; it's pretty interesting.
