Definition
A blackleg is a person who earns a living by frequenting racecourses and gambling establishments, extracting the best possible odds while paying out as little as possible. The term does not necessarily imply outright cheating or fraud — the blackleg operates within the margins of legal gambling, though close to its edge. In labor contexts, blackleg is a synonym for strikebreaker: a worker who continues working, or is hired to work, during a strike, undermining collective labor action.
1. Gambling sense: One who haunts racecourses and games of chance as an occupation, exploiting informational or positional advantages over less experienced bettors. Distinguished from a common cheat in that skill and cunning, not necessarily deception, are the defining characteristics.
2. Labor sense: A worker who refuses to join a strike or who crosses a picket line to take the place of a striking worker. In British and Commonwealth usage, this meaning is primary. In American usage, "scab" is the more common equivalent.
Common Language
Modern common usage (Wiktionary): "To continue working whilst fellow workers strike."
Historical common usage (Webster's 1913): "A notorious gambler."
The gap here is significant and time-dependent. In the nineteenth century, common and legal usage converged on the gambling meaning. By the twentieth century, common usage shifted — particularly in British English — toward the labor meaning, while the legal definitions preserved in Bouvier's and Black's reflect the earlier gambling sense. A researcher encountering "blackleg" in historical sources must anchor the term to its period: pre-twentieth century sources almost certainly intend the gambler; labor-law and trade union materials from the late nineteenth century onward may intend the strikebreaker.
Common Confusion
Blackleg and scab are near-synonyms in the labor context but carry distinct rhetorical weight. Bouvier's notes that the phrase "detestable scabs and black legs" was interpreted by courts to mean "detestable cheats and gamblers," suggesting both words were understood as terms of abuse with overlapping but not identical meanings. In defamation analysis, whether "blackleg" was understood as an accusation of cheating (a factual claim) or mere insult (opinion) was legally consequential. Researchers should not treat the two terms as interchangeable when analyzing historical pleadings or defamation actions.
Why It Matters in Research
The term is a research trap precisely because it straddles two eras and two bodies of law. In historical legal materials through approximately the 1880s, blackleg almost exclusively signals the gambling context — relevant to gaming law, vagrancy statutes, and defamation actions. In labor law materials from the late nineteenth century onward, particularly in British Commonwealth jurisdictions, it signals the strikebreaker context — relevant to trade union law, tortious interference, and labor injunctions.
Defamation cases are the most common legal vehicle for this term in the corpus. Because "blackleg" carried strong social stigma in both meanings, plaintiffs alleged it as actionable slander. The legal question often turned on whether the word, in context, imputed a specific criminal or fraudulent act or merely general social disrepute — a distinction that matters for defamation per se analysis.
Researchers using keyword searches should be alert to the term appearing in both gaming and labor law headings. A search returning "blackleg" in a labor dispute context should not be read through the gambling definition, and vice versa.
Historical Dictionary Support
All three historical dictionaries — Bouvier's, Black's (2nd ed.), and Anderson's — define blackleg exclusively in the gambling sense, with nearly identical language: a person who frequents racecourses and gaming establishments, exploiting odds without necessarily cheating. This consensus reflects the term's primary legal meaning at the time these dictionaries were compiled (late nineteenth to early twentieth century).
Black's entry is notable for appearing in close proximity to a discussion of blacklists in labor contexts, which may cause indexing confusion in the corpus but reflects editorial organization, not definitional overlap.
What the historical dictionaries miss entirely is the labor meaning, which was already in circulation in British usage by the time Black's 2nd edition was published. This omission is itself historically informative: American legal lexicography of that period was not tracking British labor law vocabulary with precision. Researchers relying solely on these dictionaries for the meaning of "blackleg" in a labor dispute will be misled.
Jurisdictional Note
In British and Commonwealth jurisdictions, the labor meaning of blackleg is primary and carries significant legal history in trade union law. In American jurisdictions, "scab" dominates labor law vocabulary and blackleg is rarely used in that sense. The gambling meaning, while obsolete in common speech, persists in the historical legal record across both traditions.