Lord Mansfield, who served as Chief Justice of the Court of King’s Bench from 1756 to 1788, achieved lasting fame by testing the limits of legal precedent. His judicial activism foretold contemporary debates about whether the law should be a closed system influenced only by judicial opinion, or whether it should be influenced by other sources, including policy concerns.

Norman S. Poser’s exhaustive Lord Mansfield: Justice in the Age of Reason paints a vivid picture of Mansfield’s life and judicial decisions, and introduces readers to the tumultuous politics and common law of the ever-lengthening eighteenth century. Poser shows deep respect for Mansfield, praising him as a moral paragon and model for modern jurists and calling him “a judge of at least equal stature with such great American jurists as John Marshall, Joseph Story, Oliver Wendell Holmes, and William Brennan.” In applauding Mansfield for his willingness to apply his moral and political vision to the common law, however, he dubiously presents Mansfield as a model for contemporary jurists.

Lord Mansfield was born William Murray, the fourth son in a Scottish aristocratic family with strong ties to the Stuarts. Among Scottish aristocrats, the deposing of the Stuart King James II from the thrones of England and Scotland still rankled, and the existence of a Jacobite court in France posed a continuing threat to the legitimacy of the English monarchs. During a 1715 Jacobite rebellion, members of Murray’s immediate family provided aid to the rebels. When the rebellion failed,