Oliver Wendell Holmes Jr. sat on the Supreme Judicial Court of Massachusetts in 1889, when, in the case of Claflin v Claflin, he joined the decision that a trust may not be modified if the intention of the testator would be undermined. Claflin rejected Lord Cottenham’s reasoning in Saunders v Vautier that, under certain circumstances, beneficiaries may compel the termination of the trust and transfer the property to them. Claflin v Claflin and Saunders v Vautier are perhaps the two most famous cases in Anglo-American Equity. Through a detailed examination of manuscripts, this article offers a comparative expansion of the US and English histories, and particularly considers the role played by Holmes. Re-enactment theory offers the possibility of creating, or reliving, the intellectual process that led to Claflin, thus revealing a significant moment in the history of US federalism.