Rosenhan's study was in two parts. The first part involved having mentally healthy participants admitted to psychiatric hospitals. This is unethical because the doctors, nurses, and other patients are being deceived. It is also unethical to observe someone without their consent, and the staff at the hospitals were being observed by the participants. For this part of the research to be approved now, it would have to be demonstrated that the real patients in the hospital would not be harmed in any way while the experiment was taking place, that the identities of all patients and doctors would be kept confidential, and the potential benefit of the information gained would be greater than the financial costs of having several people admitted to hospitals unnecessarily. The second portion of the study came when hospitals that hadn't been involved in the original experiment asserted that these results could not be achieved at their hospital.
Rosenhan said that he would have a pseudopatient admitted to their hospital within 3 months. This is unethical and perhaps even dangerous because the hospital staff could easily get carried away with determining who is healthy and who is not and potentially not give treatment to someone truly in need. Every patient admitted to the hospital during those 3 months would have been judged with Rosenhan's words in mind, and perhaps their real illness would not be dealt with properly. This part of the study also uses deception, and although the results illustrate Rosenhan's hypothesis very clearly and support his original findings, it would have to be revised to be allowed today.