However, it's important to note that frequent use of punishment during training was strongly correlated with aggressive behavior in both small and large dogs. (btoellner.typepad.com)
I think that most uses of punishment are very much for selfish interests, such as defending your position in the group. (newscientist.com)
We seek to prevent the abuses and potential repercussions of unnecessary, inappropriate, poorly applied or inhumane uses of punishment. (apdt.com)