This is the case that represents the seizure of the Supreme Court by the forces of Lord Mansfield and the deposing of the forces of Lord Camden, two British judges who led, respectively, the doctrine that questions of law should be decided only by the judge in a jury trial, and the doctrine that in a jury trial, the jury are the true judges and have the duty to judge the law as well as the facts in the case. The Mansfield doctrine has prevailed in U.S. courts ever since, extending to the state level. However, it remains controversial, and the Camden doctrine awaits a restoration.
Historically, juries in the colonial period and early decades of the Republic decided both law and fact. Their pre-eminence in judgement was unquestioned, and it was that model that the founders had in mind when they adopted the requirements for jury trials in both civil and criminal trials.
There are several ways to interpret the prevailing opinion in this case, but essentially it was a ruling that it was not a reversible error to fail to inform a jury of their right, power, and duty to decide both the law and the facts. In one sense, that was not a remarkable position, because at the time, the power and duty of a jury to decide both was general knowledge.
The problem for later jurisprudence is that courts have taken this precedent as a license to sanction defendants and their counsel for attempting to inform juries of their power and duty to decide the law. The transition from not reversing a decision for failing to inform the jury to holding a defense lawyer or his client in contempt for trying to do so is troubling for legal philosophers, and the movement to overturn this judicial practice is growing in strength.
Majority Opinion: Harlan, Jackson | Dissent: Brewer, Brown | Dissent: Gray, Shiras