Definition
Non pros is an abbreviation of the Latin non prosequitur, meaning "he does not prosecute." It is a procedural judgment entered against a plaintiff who has failed to advance an action within the time required by the rules of the court. Where the plaintiff neglects to declare, file required pleadings, or otherwise prosecute the case in due time, the defendant may enter a non prosequitur and sign final judgment, recovering costs against the plaintiff. The plaintiff in such circumstances is said to have been "non pros'd." The effect is to terminate the action.
Common Confusion
Non pros is distinct from nonsuit, though both operate against a plaintiff who has failed to proceed. Nonsuit arises at a different procedural moment — classically when the plaintiff fails to appear when called at trial or when the jury is ready to give its verdict. Bouvier's conflates the two in places by treating the judgment of non pros under his general discussion of nonsuits, which has confused readers for generations. Non pros targets failure to plead or declare in due time; nonsuit targets failure to appear at the point of verdict or, in modern usage, the voluntary or involuntary withdrawal of a case. A researcher who sees "non pros'd" in a historical record should not assume the case was voluntarily dismissed — the plaintiff may simply have missed a pleading deadline.
Why It Matters in Research
Non pros entries appear with some frequency in early American and colonial court records, English chancery and common law records, and casebooks predating the merger of law and equity. Several research traps are worth flagging.
First, terminology shifts. After the adoption of the Federal Rules of Civil Procedure in 1938 and equivalent state reforms, non pros as a formal procedural category largely disappeared from American federal practice, absorbed into the modern framework of dismissal for failure to prosecute under what is now Rule 41(b). State courts — particularly Pennsylvania, which retained non pros by statute — are the exception. Researchers working in Pennsylvania records will still encounter non pros as live procedural doctrine. In most other U.S. jurisdictions, the term survives mainly in historical records and occasionally in common speech.
Second, the abbreviation problem. In manuscript court records and docket books, "non pros" and "non suit" are sometimes abbreviated inconsistently or even interchangeably by clerks. Knowing the procedural posture — whether the matter was at the pleading stage or at trial — helps disambiguate which judgment actually occurred.
Third, costs consequences. In historical common law practice, the costs awarded on a non pros judgment were a meaningful sanction and sometimes the principal reason defendants pursued the entry. Research into litigation strategy in the eighteenth and nineteenth centuries should account for this.
Fourth, the plaintiff's remedy. A non pros judgment was not always final in the sense of precluding re-filing. Historical practice sometimes permitted the plaintiff to move to set aside the non pros on terms, paying costs. Understanding this procedural escape valve is necessary for correctly reading the outcome of terminated actions in historical dockets.
Historical Dictionary Support
Bouvier and Burrill agree on the core definition: non pros is an abbreviation of non prosequitur, operates where the plaintiff fails to declare or proceed in due time, and results in a judgment terminating the action with costs to the defendant. Both situate the doctrine in common law pleading practice.
Burrill is the more precise of the two, cleanly stating that non pros operates "where the plaintiff fails to declare in due time" and naming it as a distinct entry and judgment. Bouvier's treatment is less focused — the relevant passage appears partially under his discussion of the judgment of nonsuit and the judgment by non sum informatus, creating potential confusion between distinct procedural mechanisms. Neither dictionary addresses the doctrinal fate of non pros after procedural reform, which is the most practically significant question for researchers working across a long time span.
Both sources treat non pros as exclusively a plaintiff-side failure doctrine. That framing is accurate for classical common law procedure and remains the working definition in jurisdictions that retain the term.
Jurisdictional Note
Pennsylvania retains non pros as a distinct procedural device by statute and court rule, making it the primary U.S. jurisdiction where the term remains operationally significant in modern practice. Most other American states and the federal courts have absorbed the concept into general dismissal-for-failure-to-prosecute doctrine. English common law origins are relevant to pre-1800 colonial and early national records across all American jurisdictions.