Does anyone know what the criteria are for emotional abuse?

I have just read this article http://www.babble.com/CS/blogs/strollerderby/archive/2008/05/27/autistic-boy-voted-out-of-kindergarten-by-classmates.aspx and it said that “the state attorney’s office concluded the matter did not meet the criteria for emotional child abuse, so no criminal charges will be filed.” I do not see how this is possible. As some of you may know this is a hot button issue for me. How can this be. What constitutes emotional abuse if this does not? How have we gotten to a place in our society where this is acceptable?