Japan has long been a supporter of and an active participant in the rules-based trading system. This has allowed Japan, like many states, to engage in trade that it regards as fair and stable, liberated from superpower or great power preferences. In recent years, however, the rules-based trading system has faced challenges including from paralysis at the WTO Appellate Body arising from the United States deciding to block the appointment of Appellate Body members, accusing the body of ‘persistent overreaching’. In turn, the lack of a functioning Appellate Body allows WTO cases to be appealed ‘into the void’ of a non-functioning appeals system. Some WTO Members have made alternative temporary arrangements for an appeals system: the Multi-Party Interim Appeal Arbitration Arrangement (MPIA) which, until now, Japan had not chosen to join. Japan’s decision to now join the MPIA could be seen as a departure from its prior approach, but is in fact consistent with its long-held principles.