This paper investigates the role of due process in legitimizing the International Accounting Standards Board (IASB) and uses the development of IFRS 17-Insurance Contracts (IASB, 2017a) as a case study. It examines stakeholders’ participation and assesses the IASB’s responsiveness to the views expressed in the comment letters. It focuses on changes in recognition, valuation, and disclosure during the 10-year process, in which the Financial Accounting Standards Board (FASB) played a relevant role. For input and through-put legitimacy analysis, we conduct content analysis of comment letters and consult additional sources to understand key concerns in insurance accounting. The IASB received substantial feedback from diverse stakeholders and geographical regions, primarily preparers and European constituents. Our findings indicate that decisions throughout the standard-setting process align with stakeholders’ interests, without preferential treatment for any groups, affirming the institution’s legitimacy was preserved. This confirms that the IASB’s due process can be seen as a shield against political and constituent pressures. Nevertheless, this study cannot definitively attribute identified changes solely to comment letters, as other channels may have been equally influential.