"if they deny a man justice." This refers to not allowing a person to have what he deserves. Alternate translation: "to deny a person his rights" or "to keep a person from having what he deserves"
Doing something "in the presence of the Most High" represents doing it while knowing that God sees it. Alternate translation: "knowing that the Most High sees it" (See: [[rc://en/ta/man/jit/figs-metonymy]])