Answers to the questions of what justifies conscientious objection in medicine in general and which specific objections should be respected have proven to be elusive. In this paper, I develop a new framework for conscientious objection in medicine that is based on the idea that conscience can express true moral claims. I draw on one of the historical roots, found in Adam Smith’s impartial spectator account, of the idea that an agent’s conscience can determine the correct moral norms, even if the agent’s society has endorsed different norms. In particular, I argue that when a medical professional is reasoning from the standpoint of an impartial spectator, his or her claims of conscience are true, or at least approximate moral truth to the greatest degree possible for creatures like us, and should thus be respected. In addition to providing a justification for conscientious objection in medicine by appealing to the potential truth of the objection, the account advances the debate regarding the integrity and toleration justifications for conscientious objection, since the standard of the impartial spectator specifies the boundaries of legitimate appeals to moral integrity and toleration. The impartial spectator also provides a standpoint of shared deliberation and public reasons, from which a conscientious objector can make their case in terms that other people who adopt this standpoint can and should accept, thus offering a standard fitting to liberal democracies.