Definition
Propter affectum is a Latin phrase meaning "on account of bias or favor." In law, it designates a specific ground for challenging a juror — namely, that the juror holds some partiality, prejudice, or special relationship that is likely to prevent impartial judgment. A challenge propter affectum is not based on a juror's legal disqualification or physical defect, but on a demonstrated or presumed bias toward one of the parties, the subject matter, or the outcome of the case.
The challenge may arise from either a presumed or a proven relationship. Where the law presumes bias from a known relationship — such as kinship, financial interest, or prior service as a juror in a related matter — the challenge is said to lie propter affectum as a matter of law. Where bias must be shown through examination, the challenge is propter affectum as a matter of fact, requiring the court to evaluate the specific circumstances.
Common Language
This is pure legal Latin with no common English counterpart. The component words — affectum, from the Latin affectus, meaning disposition, feeling, or inclination — carry no independent legal meaning in English usage. The phrase functions as a technical term of art within the law of jury challenges and should be understood only in that context.
Common Confusion
Propter affectum is one of three classical grounds for challenging a juror for cause, alongside propter defectum (on account of a legal defect, such as alienage or non-age) and propter delictum (on account of a crime or infamy that disqualifies the juror). Researchers encountering historical pleading records or treatise discussions of juror challenges should take care not to conflate these three distinct grounds. Propter affectum concerns bias or partiality; it says nothing about legal competency or moral fitness, which are the domains of propter defectum and propter delictum respectively.
Why It Matters in Research
Researchers working in historical jury trial records — particularly English common law sources, colonial American practice, and early federal and state court proceedings — will encounter propter affectum as a standard pleading term without further elaboration. The phrase was used as a term of art that practitioners were expected to recognize, so period sources rarely define it inline.
The practical content of propter affectum challenges has shifted considerably over time. In classical common law, the categories of presumed bias were relatively fixed and narrow — blood relation to a party, prior knowledge of the case as a witness or arbitrator, financial stake in the verdict. Modern voir dire practice has largely absorbed and expanded the concept, with courts now inquiring broadly into juror attitudes and experiences that would not have been cognizable under the historical framework. A researcher tracing the development of impartiality doctrine should not assume continuity between the historical Latin formulation and modern bias jurisprudence; the conceptual scope has widened substantially.
In English sources, the challenge propter affectum was further divided between principal challenges (where the ground was so strong that bias was conclusively presumed) and challenges to the favor (where the party alleged bias as a factual matter, often requiring examination by triers). This subdivision appears in Coke, Blackstone, and the major common law treatises, and resurfaces in early American practice. Modern sources have generally abandoned this vocabulary, making the historical distinction a potential source of confusion when reading pre-nineteenth-century trial records.
Because Rapalje & Lawrence directs readers to the CHALLENGE entry for full treatment, researchers should treat propter affectum dictionary entries in historical sources as cross-referential placeholders rather than complete expositions of the doctrine.
Historical Dictionary Support
Black's Law Dictionary and Rapalje & Lawrence agree on the core meaning — both define the term as a challenge grounded in bias or favor — and both treat propter affectum as a subcategory within the broader law of jury challenges rather than as a freestanding doctrine. Neither source provides substantive elaboration within the propter affectum entry itself, directing readers instead to the challenge headings for full treatment.
What the historical dictionaries do not supply is any account of how the propter affectum challenge operated procedurally — who bore the burden of establishing bias, how triers were appointed to decide contested challenges to the favor, or how courts distinguished presumed from actual partiality. Researchers needing that procedural depth must look to the treatise literature rather than the dictionaries.
Jurisdictional Note
The propter affectum framework derives from English common law and was adopted broadly across American jurisdictions, but its formal Latin terminology largely disappeared from American practice by the mid-nineteenth century as statutory jury selection procedures displaced the common law challenge vocabulary. Researchers working in civil law jurisdictions will not encounter the term.
Encyclopedia Cross-Reference
See Law Mind Encyclopedia: Challenge to Jurors; Voir Dire; Jury Selection