OBJECTIVE: To determine if physicians know and can apply the legal sta
ndard for determining competence; to determine if physician assessment
of competence varies by physician age or specialty. DESIGN: Mail surv
ey with specific questions about a patient scenario and general questi
ons about the law. PARTICIPANTS: 2100 randomly selected Massachusetts
internists, surgeons, and psychiatrists. MEASUREMENTS: In Part I, the
survey presented a scenario adapted from a court case that involved an
elderly woman's refusing lifesaving surgery. The scenario was divided
into three sections: the medical history, the patient's rationale, an
d a psychiatrist's opinion that the patient was incompetent. Responden
ts were not told that an appellate court later decided the psychiatris
t applied the wrong standard of competence and the patient was indeed
competent. Respondents were asked whether the patient was competent, w
hom they would consult, and how they would respond. Part II posed a se
ries of theoretical questions about competence. Group differences were
tested by chi-square. MAIN RESULTS: Surveys were returned by 823 (41%
) of the sample. In Part I, before the psychiatrist's opinion, 58% tho
ught the patient was competent, 92% would consult a psychiatrist to he
lp assess competence, and only 17% would to go to court. After the psy
chiatrist's opinion, only 30% thought she was competent and 55% would
go to court. In Part II, 89% knew the correct standard for competence;
however, most incorrectly responded that conditions such as dementia
and psychosis establish incompetence. Psychiatrists performed signific
antly better on theoretical, but frequently worse on scenario, questio
ns. CONCLUSIONS: Physicians in general, and psychiatrists in particula
r, know the standard for competence but may apply it incorrectly. This
suggests that the common clinical practice of relying on expert medic
al opinion may introduce bias and produce inaccurate results that unde
rmine patient autonomy.