One phrase that comes up is "segregation of duties" meaning things like "if one person can do X and Y then they can commit fraud without being caught." So the principle of "segregation of duties" means that the people who can do X are on different teams than those who can do Y.
Like, specifically: please don't let your operations people in books and records have access to your treasury and reconciliation systems. Or, don't let front-office people have access to middle-office systems. See: Leeson, Nick; Kerviel, Jérôme.
