From a law perspective, corporal punishment runs a risk of overstepping the legal definition of “in loco parentis.” Secondly, the harshness of the corporal punishment is open to interpretation by all parties, and is almost always exaggerated by the child, and almost always understated by the instructor. Thirdly, there is a real legal problem when and if the corporal punishment is administered by an unauthorized employee—teachers in training, administrative personnel, gym instructors. Finally, the question of thought-out “just punishment” vs. “anger” reaction is sure to become an issue, as is equality of treatment, bias of teacher toward some individual students, racial or gender bias, whether the “rules” of corporal punishment are properly taught and enforced, etc. The financial liability of the school or school district, insurance claims, and many other complications can ensue. Actual marks of abuse, bruises, red spots, or worse, are to be properly documented by some official personnel, and will become part of the litigation.
All this is beside the question of its effectiveness, and of retaliation, especially by older students. Taken from a legal perspective, the days of ruler-slapping are over in the classroom. I can think of no “advantages” to the practice.