This thesis is about the statutes of Acton Burnell (1283) and Merchants (1285) which provided for the voluntary registration of debts before specially established registries, and sophisticated measures of execution against the defaulting debtor's person, goods, and lands. The introduction describes the sources for this thesis; the London Recognisance rolls; the certificates of statute merchant into the Chancery; the Plea Rolls of the Royal courts and of local - principally, borough - courts. Chapter 1 describes the background to the statutes, in particular the recoverability of debts before Royal, local, and mercantile courts before 1283. Chapter 2 explores the immediate legal and political contexts of Acton Burnell. A draft of the statute is discussed and compared with the statute. The need for reform in 1285 is assessed, setting Merchants alongside Westminster II n c.39. The provisions under both statutory schemes for recognition and enrolment of the debt, and the initiation of execution are described. Chapter 4 examines execution against the debtor's movable property. The statutory appraisal, sale and delivery of the debtor's goods are examined and compared both with the draft provisions and common law modes of execution. Appraisers' liability under the statutes is examined. Competing execution against the same debtor is investigated. Chapter 5 examines the debtor's arrest and detention, gaolers' statutory liability, statutory costs and damages. It investigates the operation of the statutes once the debt had been satisfied, the mechanisms for obtaining the debtor's release, and challenges to unlawful imprisonment via the writ audita querela. Chapter 6 examines execution against the debtor's immovable property. The chapter discusses the 'extent' by which the debtor's lands were to be delivered to the creditor under Merchants, and the nature of the creditor's holding of his debtor's immovables (the tenancy 'by statute merchant').