Civil proceedings, surveyed results and medical expenses that are evidenced by expert witness are just one of the methods of proof. Since a judge makes decision by synthesizing all evidences on a concerned case, thus the judgement would be different from that of expert witness. It is not rational for medical institutions, of which priorities are medical treatment, to give priority to disability decision. However, despite of its importance, medical institutions less recognize about the necessity of procedural stability and predictability in expert valuation. It is necessary to identify actual problems and investigate rational alternatives to acquire fairness in valuation procedures and accuracy in calculating future medical expenses. Therefore, this research explores the problems and realities of evaluation process in medical treatments, and then discuss the alternatives of written expert opinion and estimation of future medical expenses.