A decision must be based on relevant evidence.
This means that the findings of an investigation, or the assessment of an application, needs to be based on evidence which is persuasive, sufficient to answer the critical questions, and reliable. Mere suspicion about something is not an acceptable foundation for a decision.
A decision-maker, whether an individual or a member of a decision-making authority (for example a Committee), should only take into consideration information that is relevant to the decision to be made, and all irrelevant information should be disregarded.