In emergency situations and while medical resources are sufficient, doctors are expected to prioritize and treat patients according to medical criteria only. In MASSCAL situations and when medical resources become insufficient, patient selection and prioritization changes. Rules of triage are applied with the aim of getting the best result possible under the circumstances, e.g., saving the largest number; collective health outweighs individual health. Still, according to the standard ethical principles, non-medical criteria should never influence the doctors’ decision of who will be treated. In military contexts, so-called medical rules of eligibility (MROE) provide rules that include non-medical criteria. This chapter aims to analyze if, why, and under what circumstances it may be ethically acceptable to prioritize patients according to non-medical criteria.