This paper analyzes legal disputes and policy responses in major countries (Japan, Europe, United States, and China) in regard to standard essential patents (SEPs) with fair, reasonable, and non-discriminatory (FRAND) declarations, and examines Japan's strategy based on these analyses. In particular, recent court decisions in the European Union (EU), Germany, United States, and China, as well as competitive policy and other policy measures in Japan, United States, and EU are analyzed. In light of this, the paper discusses the legal principles that restrict the enforcement of SEPs and other specific issues including (i) how to negotiate between the patentee and the standard implementers, (ii) how to calculate the royalty that meets the FRAND conditions, (iii) how to settle disputes, and (iv) legal consequences of transfer of SEPs. The paper focuses on the legal principles that restrict the enforcement of SEPs, highlighting the existence of two approaches seen internationally: the contract law approach and the competition law approach, and then analyzing the differences between the two approaches. The paper concludes with a proposal that Japan adopts the contract law approach.