For and against - Clinical equipoise and not the uncertainty principle is the moral underpinning of the randomised controlled trial

The ethical basis for entering patients in randomised controlled trials is under debate, Some doctors espouse the uncertainty principle whereby random isation to treatment is acceptable when an individual doctor is genuinely u nsure which treatment is best for a patient. Others believe that clinical e quipoise, reflecting collective professional uncertainty over treatment, is the soundest ethical criterion. Here doctors from two Canadian centres dis cuss their positions.