Do Right By Meaning

(idiomatic, transitive) To treat, deal with, or act toward (someone) in a morally just, socially honorable fashion.

Example:   I know her new husband is a good man and wants to do right by our family.
  Hey man, did you finish that transaction with my cousin? You do right by him?
2009 August 17, Barack Obama, to the convention of the Veterans of Foreign Wars, Phoenix, Arizona, transcript
  We will do right by our troops and taxpayers, and we will build the 21st Century military that we need.
  â€¦We are not going to abandon these American heroes. We are going to do right by them.