An analysis of judicial attitudes in the United States of America towards pharmacist responsibility has shown distinct patterns or trends. Early cases set the standards for pharmacists at a high professional level. The courts later restricted liability to technical inaccuracy in prescription processing. More recently, the judiciary is recognising the necessity to apply standards appropriate to the pharmacist’s new roles and functions. A legislative gloss to these developments has been provided in the United States of America by the enactment of legislation which seeks to recognise professional roles, enhance pharmacy practice standards and improve the outcome of drug therapy for patients, by bettering patient compliance with drug regimes. There is a current expectation, particularly on the part of the public, but also on the part of health care policy makers, that pharmacists have a responsibility to detect problems with prescribed medications, and that to fail in this responsibility is a direct threat to the public health. The new expectations of drug therapy and the parallel anticipation of the participants in drug therapy have created a new duty on the part of the pharmacist, to intervene and promote the patient’s best interests. In this thesis, it is argued that this perspective is a reasonable one. Pharmacists ought to detect and prevent problems with drug therapy. The public should be disappointed if a profession, a government-sanctioned monopoly, has the ability to improve the public health but fails to do so. In turn, courts (and a legislature) that refuse to recognise expanded responsibilities for pharmacists, and that fail to impose corresponding expanded liabilities for the failure to meet a responsibility, are perpetuating an outdated view of pharmacy practice based on an incomplete understanding of the medication use system. There are solid policy reasons for imposing a higher standard for pharmacists that includes, but goes beyond, mere technical accuracy in order processing. In turn, there are limits to what pharmacists can reasonably be expected to do, and a legal system exploring the subject of expanded pharmacist responsibility should be aware of those limits.