The “Rules of Engagement(ROE)” is the control mechanism of using the force when countries execute military operations nowadays. From international practice and experience, The ROE covers the utilization in two different phases: peacetime and wartime (or can be regarded as a state of armed conflict). The dividing line is depended on the moment of using the force. In other words, the peacetime ROE limits military operations, including the use of force, to execute defensive and necessary responses to hostile acts or hostile intent in the situations of nonarmed conflict. They are premised on the right of self-defense and provided rules for the execution.

The "Law of Armed Conflict" contained in the Rules of Engagement stipulates the circumstances and ways in which a country can use force when an armed conflict occurs between countries. It does not care about the legality of the use of force. Therefore, once an armed conflict occurs, the "Armed Conflict Law" is applicable and must also comply with the principles of military necessity, distinction, proportionality, and humanity. Its purpose is to minimize the suffering, loss, and destruction caused by war. Taking maritime military operations as an example, the formulation of the rules of engagement should not only consider the "Law of Armed Conflict", but also reflect the "United Nations Charter", "International Humanitarian Law" and " United Nations Convention on the Law of the Sea" and other relevant international laws and regulations.

This thesis reviews the history and development process, the basic principles and forms, the legal status and connotation, and the requirements and application timing of the ROE in peacetime. By understanding the specific practice and the possible appearance of the international ROE, and possible uses of ROE in the waters surrounding Taiwan is discussed. During the time that our country is developing ROE policy now, we hope to provide more systematic research and analysis to attract domestic academic circles or national defense policy units to have a deeper understanding and discussion on the issue of ROE.