One way of thinking about whether medical school candidates' personalities should influence admission is to ask the question, "Would you want this person to care for one of your loved ones?"
Applicants to medical school are expected to live by their presentation of themselves and of their commitment to medical practice. It is not just a retrospective report but also a promise to which admissions officers should be able to expect them to adhere.
It is unconstitutional--and unethical--for physicians to participate in evidence-gathering against pregnant women suspected of being addicted to illegal substances without informing them of their constitutional rights or gaining their informed consent.