How to Distinguish between Righteous and Unrighteous Anger

There are times when it’s hard to tell if a person’s anger is righteous or not. Of course, there is the added issue of thinking the best of ourselves when it comes to our anger. Thus, the temptation to reclassify our angry moments is alluring. Righteous anger is the term we use to describe someone who is not sinning when angry; it is possible to be angry and sin not, but the question is, how do you know if your anger is righteous or unrighteous? What does righteous anger do that sinful anger cannot?