Definition
*Plegi de prosequendo* (Latin: "pledges to prosecute") is a formal undertaking in the old action of replevin by which the plaintiff provided sureties — pledges — guaranteeing that the plaintiff would prosecute the action to effect. In practical terms, it was a security requirement imposed at the outset of replevin proceedings: before the plaintiff could recover possession of distrained or seized goods, the plaintiff was required to produce pledges (sureties) who would answer for the plaintiff's diligent and good-faith pursuit of the case. The requirement served as a check against frivolous or abandoned replevin suits, ensuring that the defendant would not be deprived of the goods — and left without recourse — if the plaintiff simply walked away from the litigation.
Common Confusion
PLEGI DE PROSEQUENDO vs. PLEGII DE RETORNO HABENDO: These are the two distinct pledge obligations in replevin. *Plegi de prosequendo* secured the plaintiff's promise to prosecute the action; *plegii de retorno habendo* secured the plaintiff's promise to return the goods to the defendant if judgment went against the plaintiff. Both sets of pledges appear on the same writ or record, and both had devolved into formal fictions by the eighteenth century. Mixing them up produces a fundamental misreading of which risk — prosecution or return — is being guaranteed in a given source.
Why It Matters in Research
This term appears almost exclusively in sources dealing with the medieval and early modern common law action of replevin, which makes it primarily of historical interest. Researchers will encounter it in Year Books, early English plea rolls, writs of replevin, and treatises on common law procedure. It is essentially absent from modern practice, having disappeared along with the formal pledge and surety requirements that characterized pre-reform civil procedure.
The key trap for researchers: *plegi de prosequendo* is one of several distinct pledge requirements embedded in replevin practice. Do not conflate it with the *plegii de retorno habendo* — the pledges to return the goods if the plaintiff lost the action — which served an entirely different function. Historical sources, including older treatise writers, sometimes refer to both sets of pledges in close proximity, and a reader unfamiliar with the distinction can easily misread which obligation is being described.
When working in the Law Mind corpus, this term connects directly to the broader procedural architecture of replevin: the writ, the return, the avowry, and the counter-pleading forms. It also connects to the history of suretyship in common law procedure, where pledges functioned not as real parties but as process-enforcement mechanisms — a feature that distinguishes them from modern sureties in the contractual or bond sense.
Because the pledges *de prosequendo* were largely a formal fiction by the later common law period — courts and clerks recorded them without meaningful investigation of the sureties' identity or substance — researchers should treat their presence in a record as procedural boilerplate rather than evidence of a real transaction.
Historical Dictionary Support
Black's Law Dictionary (2nd ed.) defines the term concisely as "pledges to prosecute with effect an action of replevin." This is accurate as far as it goes, but the entry provides no procedural context and does not distinguish *plegi de prosequendo* from its companion pledge requirement, *plegii de retorno habendo*. The absence of that distinction is the most significant gap in the historical dictionary treatment. No other shelf sources in the current Law Mind corpus provide an independent entry for this term. Researchers needing deeper treatment should consult Blackstone's *Commentaries* (Book III, on the action of replevin) and Fitzherbert's *Natura Brevium*, both of which address the pledge requirements in their procedural setting.
Jurisdictional Note
This term is a creature of English common law procedure. American courts inherited replevin but modernized it substantially through statutory reform; the formal pledge requirements, including *plegi de prosequendo*, were abandoned in virtually all American jurisdictions well before the twentieth century. The term is not operative in any modern common law jurisdiction.