Answer： 1) The definition of protocol violations can be referred to the following documents: a) 21 CFR 812.150 (a) (4) The FDA Center for Device and Radiological Health: Deviations from the investigational plan b) The International Standards Organization "Document 14155: Clinical Investigation of Medical Devices For Human Subjects Good Clinical Practice: Deviation is instance (s) of failure to follow, Intentionally or unintentionally, the requirement of the Clinical Investigational Plan d) ICH E3 Guidelines for Industry: Structure and Content of Clinical Study Reports, Questions&Answers: A protocol deviation is any change, divergence, or department from the study design or procedures defined in the protocol e) ICH E6 R2 sections 3.3.7, 4.5.2, 4.5.3, and 4.5.4 stipulate that researchers need to follow the protocol and provide recommendations for handling protocol violations. f) Guiding principles for ethical review of drug clinical trials. 2) Grading of protocol deviations. Firstly, clarify the protocol