Nebraska Revised Statute 29-439
Chapter 29 Section 439
Domestic assault; arrest; conditions; report required.
(1) If a peace officer receives complaints under section 28-323 from two or more opposing persons, the officer shall evaluate each complaint separately to determine who was the predominant aggressor. If the officer determines that one person was the predominant aggressor, the officer need not arrest the other person believed to have committed an offense. In determining whether a person is the predominant aggressor, the officer shall consider, among other things:
(a) Prior complaints under section 28-323;
(b) The relative severity of the injuries inflicted on each person;
(c) The likelihood of future injury to each person; and
(2) In addition to any other report required, a peace officer who arrests two or more persons with respect to such a complaint shall submit a detailed, written report setting forth the grounds for arresting multiple parties.