Definition
Latin: "I am not informed." A formal declaration made by a defendant's attorney in court indicating that counsel has received no instruction or advice from the client regarding any defense to be raised against the action. The effect of this declaration is procedurally decisive: it operates as a concession that no defense will be offered, upon which the court enters judgment by default against the defendant.
The phrase functioned as a term of art within common law pleading practice. Rather than contesting the plaintiff's claim or requesting additional time, the attorney's utterance of informatus non sum formally closed the pleading stage on the defendant's side, triggering the default mechanism as a matter of course.
Common Confusion
Informatus non sum should not be confused with a general demurrer or a plea in abatement, both of which involve affirmative procedural responses to the plaintiff's claim. Nor is it equivalent to a failure to appear, which is an unannounced absence. Informatus non sum is a deliberate, spoken declaration made by counsel who is present in court — an active, if resigned, procedural act rather than passive omission. The distinction matters when reading historical records: a court entry noting this phrase signals an intentional formal surrender, not a missed appearance.
Why It Matters in Research
This term belongs almost entirely to the historical common law pleading world and will not appear in modern procedural codes or contemporary case law. Researchers encountering it should expect to find it in:
— English common law court records and Year Books predating modern civil procedure
— American state court records from the colonial through early nineteenth-century periods, when common law pleading forms remained in active use
— Treatises on common law pleading, such as those of Chitty and Stephen, which describe the mechanics of default and formal pleading declarations
The procedural significance is that informatus non sum did not merely result in default as a consequence of inaction — it was itself the formal trigger. This distinction affects how historians and legal researchers read docket entries and court records: the phrase marks a conscious, attorney-executed procedural step, not an oversight.
Researchers should also be aware that this term effectively disappears from American practice after the adoption of the Field Code in New York (1848) and the subsequent spread of code pleading across jurisdictions, which swept away most Latin pleading formulas. By the time of the Federal Rules of Civil Procedure (1938), the term had no functional analog in standard American practice. Its appearance in a source after roughly the mid-nineteenth century in American materials is unusual and warrants attention to the nature and jurisdiction of the source.
The term has no current operational meaning in any major common law jurisdiction's procedure. It survives only as a historical artifact and as a dictionary entry useful for decoding older primary sources.
Historical Dictionary Support
Both editions of Black's Law Dictionary consulted agree precisely on the definition, offering nearly identical text: an attorney's formal declaration that he has not been advised of any defense, upon which judgment by default passes. The entries are brief and functional, treating the phrase as self-explanatory within the common law pleading context.
What neither edition addresses is the procedural mechanics surrounding the declaration — when in the proceedings it was made, whether it could be retracted, or how it interacted with motions for continuance. Historical pleading treatises fill this gap more fully than the dictionary entries do. Researchers needing deeper procedural context should look to period-specific common law pleading manuals rather than relying on dictionary entries alone.
Neither edition flags the term's obsolescence explicitly, which is a meaningful omission: a researcher encountering Black's without context might not appreciate that the term had already passed out of active American use by the time the first edition was published (1891).
Jurisdictional Note
The phrase is rooted in English common law practice and migrated with it into early American courts. Its use was not uniform across colonies and early states, and its displacement by code pleading occurred at different times in different jurisdictions throughout the nineteenth century. It retains no procedural effect in any current U.S. jurisdiction.