Background: A resilient issue in research ethics is whether and when a placebo-controlled trial (PCT) is justified if it deprives research subjects of a recognized treatment. The clinician’s moral duty to provide the best available care seems to require the use of ‘active’ controlled trials (ACTs) that use an established treatment as a control whenever there is an established therapy. On the other hand, ACTs are supposedly methodologically inferior to PCTs. Hence, the moral duty of the clinical researcher to use the best methods will favour PCTs. However, the alleged methodological superiority of PCTs over ACTs has escaped sustained analysis. Objectives: To analyze and critique the supposed methodological superiority of PCTs over ACTs. Methods: Search for and describe the various arguments that PCTs are methodologically superior to ACTs, namely: (1) ACTs lack ‘assay sensitivity’; (2) ACTs do not measure absolute effect size; and (3) ACTs require more participants. Results: None of the arguments stand up to scrutiny. Consequently the tension between clinical and research ethics dissolves: the moral duty of the clinician to avoid PCTs is unopposed by methodological considerations. Ethics committees and IRBs should scrutinize requests to conduct PCTs more carefully and the World Medical Association’s Declaration of Helsinki should revise its stance on PCTs.