The U.S, Constitution-- heard of it?-- demands that the government cannot deprive citizens of life without due process of law.
It is possible that the people hit by the drone strikes have had some legal process applied to who gets targeted... but due to the secrecy, we don't know that. From all the evidence I can see, the "due process" is that one CIA guy says "I think this person should be on the list."
When I was a kid, you could tell which countries were dictatorships: those were the ones who had secret courts and secret police with secret powers with no limits and no oversight. In German, there is even a word for such secret police-- "Geheime Staatspolizei", literally "secret state police." More commonly called the Gestapo.
Now I live in a country with secret courts and secret police. I don't like it.
What is that due process, how is it implemented, and by whom? Without that question answered, we live in a dictatorship, and simply don't know it.