The decision making process needs to be valid and reproducible. Although there are a number of triage systems available for mass casualty incidents, there has been little validation of any of them in the field [34] , and what there has been relates to 'big bang' single incidents and the apparent unreliability of triage [35, 36] . While it does not need to be explicit ahead of time, the decision thresholds should be based on both the cumulative evidence about the disease process and prognosis, and the number of patients and severity of illness making the demands on the service [31] . In effect, triage may result in a gradual degradation of care with the increasing scale of the incident and become a 'societally mandated Do Not Resuscitate order'. On these grounds the process needs to be carefully considered at an appropriately senior level and applied consistently [32] .