Should scientific facts and methods have an epistemically privileged status in public reason? In Rawls’s public reason account he asserts what we will label the Scientific Standard Stricture: citizens engaged in public reason must be guided by non-controversial scientific methods, and public reason must be in line with non-controversial scientific conclusions. The Scientific Standard Stricture is meant to fulfill important tasks such as enabling the determinateness and publicity of the public reason framework. However, Rawls leaves us without elucidation with regard to when science is and is not ‘non-controversial’ and more importantly, we are left without a justification for a stricture which excludes certain controversial beliefs and methods of inquiry from the realm of political justification. In this article, we offer what we deem to be the most plausible interpretation of Rawls’s Scientific Standards Stricture. We then use Rawls’s general theoretical framework to examine various potential justifications for privileging these ‘non-controversial’ scientific methods and conclusions. We conclude that no viable justification is available to Rawls.