In novel cases, judges often weigh policy considerations based on common sense assumptions and personal experience about how certain individuals, groups and institutions behave. For example, in assessing the consequences of creating a new category of duty of care, a new immunity from suit or even a new tort, judges are invited to predict (or speculate about) how individuals, groups, professions and institutions would behave if the law was different. In routine cases, judges also rely on assumptions and experience in deciding questions of reasonableness and past hypothetical facts about causation. In deciding both novel and routine cases on the basis of assumptions and experience, judges are prone to cognitive biases that affect decision-making in general.
Justice Peter Applegarth, Deciding Novel and Routine Cases without Evidence [Draft as at 12 September 2018], Journal of Tort Law. Published Online: 2018-10-02. DOI: https://doi.org/10.1515/jtl-2018-0011.