Ignacio Luis Vallarta was instrumental in establishing notions of binding case law (jurisprudencia) in amparo actions (actions to protect constitutional rights) in nineteenth-century Mexico. This article examines Vallarta's reports of cases in the Mexican Supreme Court and his other writings to explore this concept in relation to his drafting of the Amparo Act of 1882. The work concludes that it is overwhelmingly clear from the works and statements of Vallarta that Mexican jurisprudencia in constitutional law is predominantly a product of direct borrowing of United States legal methods.