Definition
A labor union is an organized association of workers formed to advance their collective interests in the employment relationship. Acting as a collective bargaining representative, a union negotiates with employers over wages, hours, working conditions, and other terms of employment. In the United States, recognized unions typically hold the exclusive right to represent a defined bargaining unit — a group of employees sharing a community of interest — and are legally obligated to represent all members of that unit fairly, regardless of individual union membership.
The term is functionally synonymous with "trade union" in American usage, though "trade union" carries stronger historical associations with craft-based organization. Both refer to the same legal entity under federal labor law.
Common Language
Modern common usage (Wiktionary): A continuous association of wage-earners for the purpose of maintaining or improving the conditions of their employment; a trade union.
Historical common usage (Webster's 1913): Not separately defined as a legal term; "union" in ordinary usage denoted simply a joining together or combination of persons or things for a common purpose.
The common and legal meanings are closely aligned today, but the gap matters historically. In the nineteenth and early twentieth centuries, describing a workers' combination as a "union" carried no legal protection — it was a descriptive social term for an entity that courts might simultaneously recognize as a criminal conspiracy. The legal legitimacy now embedded in the common meaning is entirely a product of statutory development, not inherent in the word itself.
Common Confusion
Labor union is sometimes used interchangeably with trade union, employee association, or collective bargaining representative. These terms are largely coextensive in modern federal labor law, but the distinctions matter at the margins. An employee association in the public sector may lack full collective bargaining rights depending on state law. A professional association (a bar association, a medical society) is not a labor union even if it advocates for members' professional interests, because it does not function as an exclusive bargaining representative under labor statutes. Researchers using historical sources should also note that "combination" and "society of workmen" were the functional predecessors of the term "labor union" in English and early American legal writing.
Why It Matters in Research
The legal status of labor unions inverted dramatically between the mid-nineteenth century and the mid-twentieth century. Before the Norris-LaGuardia Act (1932) and the National Labor Relations Act (1935), unions operated in a hostile legal environment — their concerted activities were routinely challenged as common law conspiracies or restrained by injunction. Corpus research in cases and treatises from roughly 1800 to 1930 will find the term "labor union" treated with legal suspicion rather than legal legitimacy. Researchers must read sources from that period with that background assumption in place.
After 1935, federal law created an affirmative framework recognizing and regulating unions. The corpus therefore reflects two entirely different legal universes depending on the date of the source. Secondary materials that do not anchor their analysis to a specific statutory regime may conflate pre- and post-NLRA frameworks, producing misleading generalizations.
Additional layers of complexity arise from coverage gaps in federal law. The Railway Labor Act governs railroads and airlines under a separate statutory scheme. Public sector workers are covered — if at all — by state law, not the NLRA, and coverage varies widely. Research into public sector labor relations (including teachers, police, and government employees) requires state-specific analysis. Materials in the Law Mind corpus on public sector labor should be read with the understanding that there is no single federal floor governing those workers' organizing rights.
The duty of fair representation — the union's obligation to represent all bargaining unit members without arbitrary or discriminatory conduct — is an implied statutory obligation developed through case law, not explicit in the text of the NLRA. Researchers looking for this concept in early post-NLRA sources may not find it under that name.
Historical Dictionary Support
Bouvier's Law Dictionary defines a labor union as a combination or association of laborers for the purpose of fixing wages and hours, for mutual benefit and protection, and for the redress of grievances against employers. Bouvier then traces the English legal background, noting that when wages were fixed by law or magistrate, and statutes criminalized covenants among workmen to refuse work except at certain rates, a combination to withhold labor was treated as criminal conspiracy. This reflects the foundational tension in Anglo-American labor law: that collective action by workers, viewed through the lens of combination and conspiracy doctrine, was legally indistinguishable from a criminal plot.
Bouvier's entry, by focusing on the criminal conspiracy lineage, captures the pre-statutory common law posture accurately. What it cannot capture — given its era — is the subsequent statutory displacement of that framework. The entry is valuable precisely as a baseline for understanding how far the law moved: from treating unions as presumptively criminal combinations to treating them as legally protected and federally regulated institutions. Modern sources must supply the transformation Bouvier could not anticipate.
Jurisdictional Note
Federal labor law under the NLRA governs most private sector workers but expressly excludes agricultural workers, domestic workers, supervisors, and independent contractors. Public sector labor relations are governed entirely by state law, with wide variation — some states grant full collective bargaining rights, others permit only meet-and-confer arrangements, and a small number prohibit public sector collective bargaining altogether.
Encyclopedia Cross-Reference
The Law Mind Employment & Labor Law Encyclopedia:
— The Railway Labor Act and Transportation Industry Labor Law
— Public Sector Labor Relations