This contribution examines the idea that partisan witness preparation in criminal trials in the United States amounts to a comparative anomaly in the common law context. In American procedure, parties are not constrained by straightforward rules and ethical canons in their choice and deployment of preparation techniques, save for a prohibition on subornation and use of perjury. The lax regulation of pre-trial witness interviews in the US contrasts with the stricter rules on professional conduct of barristers and prosecutors in England and Wales and the cautious attitude towards extensive witness preparation prevailing in Canada, Australia, and New Zealand. These divisions mark deep-seated differences between these countries in what fact-finding arrangements are deemed optimal in the criminal process and what importance is given to witness spontaneity as opposed to a leeway for parties to shape the evidence submitted for evaluation to the fact-finder. Although comparative divergence alone does not render the US approach ‘anomalous’, the difficulty of reconciling its liberal practice with the trial system’s quest for the truth in a sense justifies this label. Some of the excesses of the current practice could be remedied and the truth-finding objective given a more prominent place in the criminal process if a stricter approach were taken towards the regulation of witness preparation in the US and legal and ethical norms were aligned more closely to establishing the truth. In distinguishing between ethical and unethical conduct, the rules should consider not only the mental element of counsel but also the objective effects of preparation on the authenticity and accuracy of witness recollection. While more research into such effects is needed, the article argues tentatively that the most suggestive and therefore objectionable techniques used in the US should be abandoned or subjected to more rigorous regulation.