Some people in modern American culture do not seem comfortable with the concept of labeling actions as "evil," or even using the softer word "wrong." I have less trouble, which leads my mother to often charge me with wanting simple solutions to complex problems. While I agree that in life, there are many shades of grey, there are behaviors and actions that I have little problem with labelling right or wrong. Granted, I have more trouble with right. For that, see the problems of unintended consequences, meddling, and the winners writing the history books.
However, the concept of evil for me is more sharply defined than Supreme Court Justice Potter Stewart’s definition of obscenity – famously, "I know it when I see it" (1964). To paraphrase another quote, this time by modern fantasist and novelist Terry Pratchett (no accredited ethicist but a sharp observer of human nature), evil begins with treating people as objects and goes on from there.