Utah Predominant/Dominant Aggressor Law
77-36-2.2. Powers and duties of law enforcement officers to arrest — Reports of domestic violence cases — Reports of parties’ marital status.
(3) If a law enforcement officer receives complaints of domestic violence from two or more opposing persons, the officer shall evaluate each complaint separately to determine who the predominant aggressor was. If the officer determines that one person was the predominant physical aggressor, the officer need not arrest the other person alleged to have committed domestic violence. In determining who the predominant aggressor was, the officer shall consider:
(a) any prior complaints of domestic violence;
(b) the relative severity of injuries inflicted on each person;
(c) the likelihood of future injury to each of the parties; and
(d) whether one of the parties acted in self defense.