Objective: The aim of this study is to review issues of legal liability in prescribing choice. Prescribing not only occurs in a medical setting, but also in a social and legal context in this era of evidence-based medicine and greater consumer awareness. Prescribers may be unaware of the legal consequences of medical decision-making and prescribing choice. This issue affects all areas of medicine and can be illustrated by antidepressant choice for major depression.

Method: A review was undertaken of liability issues that may arise in the context of prescribing, with particular reference to prescribing antidepressants. Results: There are legal precedents which illustrate prescribers' potential liability. These impose duties on the prescriber including those of care, to inform, and to respond to patients' wishes. In particular, the duty of care requires that if medicines are of equal efficacy, one should prescribe the best tolerated and least toxic medicine that is most likely to be taken at an effective dose for an adequate duration. While older and newer antidepressants are generally of equal efficacy, the newer agents have higher tolerability, lower toxicity and are less likely to be associated with treatment failure (due to sub-therapeutic dose regimens, or the patient discontinuing medication), disabling psychomotor impairment, dietary interaction or fatal overdose.

Conclusions: There needs to be compelling reasons for prescribing medicines with a greater likelihood of adverse outcomes such as the older antidepressants (e.g. tri-cyclics) rather than the newer antidepressants such as RIMAs, SSRls, SNRls and 5HT₂ receptor antagonists. The higher likelihood of an adverse outcome of treatment where an older antidepressant has been prescribed raises the potential for professional negligence claims to be brought against medical practitioners who prescribe such medicines for reasons other than established medical need.