隨著醫療臨床用血和血液製品使用的大量增加，患者因血液製劑中存在病毒而感染梅毒、肝炎、甚至愛滋病的情況已屢見不鮮。無論是與輸血感染相關的醫療過失訴訟，還是與血液製品感染相關的藥害訴訟，如何認定過失和因果關係成為加害人與被害人之間爭議的焦點所在。在醫療過失案件中，日本最高裁判所對醫生課以高度注意義務，甚至是「最善的注意義務」。並且，其明確指出，過失判斷是法律判斷，應當區別於醫學判斷，醫生遵循醫學慣例並不必然得出不存在醫療過失的法律結論。在醫療訴訟和藥害訴訟中，裁判所認定因果關係時，適用「高度蓋然性」法理。尤其是在重複感染案件當中，裁判所積極運用經驗法則，對因果關係在事實上進行推定，相當具有借鑒意義。在藥害訴訟中，裁判所還根據藥品有效性與副作用的比較分析來進行產品缺陷的判斷。此外，在因使用血液製劑所導致的大規模感染（例如，集團感染愛滋病或C型肝炎）事件中，為了更好地救濟受害人，在民事司法救濟之外，國家賠償責任的承擔以及立法、行政救濟亦很重要。

In medical community, the blood is called ＂the source of life.＂ However, in recent years, due to transfusion of blood and blood products, there is a significant increase of patients who have been infected by virus such as HBV, HCV or HIV. Japan also had the same problem like us but succeeded in dealing with it. This paper intends to introduce and analyze the Japanese court’s relevant judgments in recent years, sort out the main issues of this legal theory from discussing the feature of the blood, medical negligence, causation, assignment of responsibility while attempting to provide a reference for China to provide legal remedies for the victims.