Definition
A Roman civil law term denoting the criminal offense of extortion accomplished through threats of violence. Concussio described the act of compelling a person to surrender money or property by placing them in fear of bodily harm or other violent consequences. The term derives from the Latin verb *concutere*, meaning to shake violently or strike together, capturing the coercive force that defined the offense. Under Roman law, concussio was treated as a distinct wrong separate from simple theft or fraud, precisely because it operated through intimidation rather than deception or stealth.
The offense is addressed in the Digest of Justinian at Title 47.13, which provided the classical legal framework for prosecuting this form of coercive extortion in Roman courts.
Common Confusion
Concussio is sometimes loosely equated with extortion generally, but Roman jurists drew meaningful distinctions between concussio (extortion by threats of violence), *repetundae* (extortion by public officials abusing their office), and *rapina* (violent taking of property). These are related but not interchangeable concepts. A researcher encountering any of these terms in translated Roman law sources should not treat them as synonyms.
Why It Matters in Research
Concussio is a term of Roman civil law with no direct survival in modern common law doctrine. Researchers will encounter it almost exclusively in three contexts: (1) translations of or commentaries on the Corpus Juris Civilis, particularly Digest 47.13; (2) historical treatises on Roman criminal law; and (3) early modern civil law scholarship that drew on Roman categories to analyze extortion and related offenses in continental European legal systems.
The term does not appear in Anglo-American case law as an operative legal concept. If a historical source uses concussio in an English or American legal context, it is almost certainly either a borrowed civilian term used for rhetorical or comparative purposes, or evidence of civil law influence on a particular jurisdiction or writer.
Researchers working on the history of extortion law should note that modern Anglo-American extortion doctrine developed through entirely different channels — principally through common law writs, statutes of extortion targeting official misconduct, and eventually criminal codes — without formal adoption of the Roman concussio framework. The conceptual overlap is real, but the lineage is not direct.
One navigational trap: some older dictionaries and treatises treat concussio and extortion as simple equivalents, which can obscure the more precise distinctions Roman law drew among different coercive offenses. Burrill's entry, for instance, offers no more than the Digest citation and a one-line gloss, which is sufficient for identification but not for understanding how the offense functioned in Roman legal practice.
Historical Dictionary Support
All three source dictionaries — Black's (1st ed.), Black's (2nd ed.), and Burrill's — are in complete agreement: concussio is the Roman civil law offense of extortion by threats of violence, with Digest 47.13 as the authoritative source. The entries are nearly identical across all three, reflecting the term's settled, narrow meaning within the legal dictionary tradition. None of the historical dictionaries elaborate on how the offense was prosecuted, what remedies were available, or how Roman jurists distinguished it from neighboring offenses. For that level of analysis, the Digest itself and secondary scholarship on Roman criminal law are necessary. The dictionary entries are useful for quick identification only.
Jurisdictional Note
Concussio is a Roman law term with no operative role in common law jurisdictions. It retains relevance in civil law systems with Roman law roots, particularly in European legal history scholarship. Researchers working in Louisiana, Quebec, or other mixed civil-common law jurisdictions may encounter it in historical sources but should not expect it to carry doctrinal weight in modern courts.