This column at Pajamas Media gives some sense of the ethical dilemmas faced in medical research:
How informed is informed? What is the psychological effect of being told of every last possible complication of a treatment? Do all people react the same way to information, or does their reaction depend upon such factors as their intelligence, level of education, cultural presuppositions, and if so does the informing doctor have to the account of them, and if so how and to what degree? An orthopedic surgeon once told me that obtaining informed consent from patients now takes him so long that he had had to reduce the number of patients that he treats.