The dual nature of the word "sanction" drives me up the wall. I avoid using it, and when I do use it I do so exclusively in its original, positive context. There are plenty of words to use in place of "sanction" in a negative context.

"The verb form has traditionally related to the positive meaning, not the negative one. Thomas Jefferson wrote in his autobiography of preserving 'the very words of the established law, wherever their meaning had been sanctioned by judicial decisions.'"

Click here for a short article from the Wall Street Journal on the word and its usage over time.