Dictionaries adapt to popular usage, so unless your argument is that popular usage is correct usage - dictionaries aren't good support either. Check the word origin, it originally distinguished those who are subject to civil law and those who aren't (US service members are subject to the Uniform code of military justice). Over the last couple hundred years it became less specific and was used to distinguish belligerents from the civil. More recently (as in I don't remember it being used this way 20 years ago) it has been used to distinguish those with authority from the lesser-thans.

I prefer the old definition, because now - due to the corruption of the word, we have no unambiguous word to describe the original concept. We already have plenty of words to describe those without authority.