The ethics of the Flexibility In duty hour Requirements for Surgical Trainees trial have been vehemently debated. Views on the ethics of the FIRST trial range from it being completely unethical to wholly unproblematic. The FIRST trial illustrates the complex ethical challenges posed by cluster randomised trials of policy interventions involving healthcare professionals. In what follows, we have three objectives. First, we critically review the FIRST trial controversy, finding that commentators have failed to sufficiently identify and address many of the (...) relevant ethical issues. The 2012 Ottawa Statement on the Ethical Design and Conduct of Cluster Randomized Trials provides researchers and research ethics committees with specific guidance for the ethical design and conduct of CRTs. Second, we aim to demonstrate how the Ottawa Statement provides much-needed clarity to the ethical issues in the FIRST trial, including: research participant identification; consent requirements; gatekeeper roles; benefit-harm analysis and identification of vulnerable participants. We nonetheless also find that the FIRST trial raises ethical issues not adequately addressed by the Ottawa Statement. Hence, third and finally, we raise important questions requiring further ethical analysis and guidance, including: Does clinical equipoise apply to policy interventions with little or no evidence-base? Do healthcare providers have an obligation to participate in research? Does the power-differential in certain healthcare settings render healthcare providers vulnerable to duress and coercion to participant in research? If so, what safeguards might be implemented to protect providers, while allowing important research to proceed? (shrink)