Informed consent is potentially at odds with distributive justice.
I have occasionally volunteered to be a subject in research studies that were uncomfortable and of unlikely personal benefit. Further complicating matters, the distribution of supposed medical justice before the therapeutic possibilities are discovered by scientific study is a reversal of common sense. Clinical trials sometimes expose favorite therapies and standards of care as bad medicine. The prevention of trials on the basis of a priori guesses about outcomes and downstream effects on therapeutic justice demonstrates a misunderstanding of science and risks delaying improvements in standards of care. The unquestioned principle of fully informed consent should be powerful enough to cover issues of the distribution of benefits and risks.