Definition
A subagent is a person appointed by an agent to perform all or part of the work that the appointing agent was engaged by the principal to carry out. The subagent acts within the chain of authority originating with the principal but is deployed by the agent rather than by the principal directly.
The key structural feature of subagency is that authority flows through two layers: principal → agent → subagent. This layered structure raises distinct questions about who bears liability for the subagent's conduct and whether the subagent can bind the principal in the same manner as the original agent.
Common Language
Modern common usage (Wiktionary): A person employed by an agent to transact the whole, or a part, of the business entrusted to the latter. (Wiktionary also flags a modern technology usage: an autonomous process launched by another agent to handle part of that agent's task — a usage entirely outside the legal context.)
Historical common usage (Webster's 1913): A person employed by an agent to transact the whole, or a part, of the business intrusted to the latter.
The common and legal definitions align closely here, but the legal meaning carries significant additional weight. In ordinary usage, a subagent is simply a helper employed by an agent. In law, that relationship determines liability allocation, the scope of authority the subagent can exercise, and whether the principal is bound by or answerable for the subagent's acts — questions the common definition does not address.
Common Confusion
Subagent is frequently confused with two adjacent figures: the servant or employee of the agent, and the independent contractor retained by the agent. A subagent, properly understood, acts on behalf of the principal, not merely on behalf of the agent as an employer. This means a subagent can, under the right conditions, bind the principal and expose the principal to third-party liability — a consequence that does not automatically follow when an agent merely hires a worker to assist with personal tasks. Researchers should also distinguish subagency from co-agency, where two agents are independently appointed by the same principal; a co-agent's authority traces directly to the principal, while a subagent's authority traces through the appointing agent.
Core Elements
Three issues define the legal significance of a subagency relationship:
Authorization. An agent generally has no implied power to appoint a subagent. Authority to delegate must be express, arise from custom, be implied by the nature of the undertaking (e.g., the task cannot reasonably be performed without delegation), or be ratified by the principal after the fact. Without proper authorization, the appointing agent may be liable to the principal for any resulting harm.
Privity and liability. When a properly authorized subagent is appointed, the subagent typically stands in privity with the principal for purposes of the work performed. The principal may be bound by the subagent's authorized acts and may be liable to third parties for torts committed within the scope of that authority. The original agent retains responsibility to the principal for the subagent's performance.
The unauthorized subagent. Where delegation was not authorized, the person appointed is more accurately characterized as the agent's own contractor or servant, not the principal's subagent. The principal is generally not bound by or liable for such a person's acts, and the appointing agent bears full responsibility.
Why It Matters in Research
Subagency doctrine is where agency law gets genuinely complicated, and historical sources require careful reading. Pre-twentieth-century cases and treatises often used "subagent" loosely to cover both properly authorized subagents and unauthorized delegates, without clearly distinguishing liability consequences. Researchers working in nineteenth-century case law should not assume that a court's use of the word "subagent" means the court found actual authorized delegation — the term was sometimes used descriptively rather than legally.
The question of when implied authority to delegate arises has also shifted. Earlier sources, including Kent's Commentaries, reflected a stricter rule: delegation was disfavored and required clearer authorization. Modern agency law (as restated in the Restatement (Third) of Agency) acknowledges broader implied authority to delegate routine tasks, particularly in commercial contexts. Researchers should be alert to which era's standard a source is applying.
Jurisdictional variation in broker subagency is a practical trap. Real estate brokerage extensively uses "subagency" to describe the relationship between a listing broker and cooperating brokers from other firms. The liability rules in this context are heavily shaped by state licensing law and MLS rules, and do not track general agency doctrine cleanly. Many states have significantly restructured or abolished traditional subagency in real estate through statute since the 1990s. Sources predating those statutory reforms may state rules that no longer hold.
Historical Dictionary Support
Black's Law Dictionary (both the first and second editions) defines subagent identically as "an under-agent; a substituted agent; an agent appointed by one who is himself an agent," citing 2 Kent's Commentaries at 633. Webster's 1913 and Wiktionary's historical layer replicate substantially the same formulation, tracing to Bouvier and Chitty.
The convergence across sources is notable: every historical authority defines the term structurally (positional relationship in the chain of authority) rather than functionally (what authority the subagent holds or what liability attaches). This reflects the era's approach — the dictionaries capture the architecture of the relationship without resolving the harder doctrinal questions that courts and treatises addressed separately. Researchers should treat these definitions as starting points, not as statements of liability rules.
Jurisdictional Note
Real estate subagency is the area of most significant jurisdictional divergence. Most U.S. states have enacted disclosure and consent statutes, or adopted MLS rules, that have effectively replaced traditional subagency with buyer-broker agreements and other alternatives. A researcher analyzing brokerage liability should verify current state law rather than relying on pre-1990s common law rules. Outside the real estate context, subagency doctrine follows general agency principles across most common-law jurisdictions, though the Restatement (Third) of Agency's formulations have not been uniformly adopted.
Encyclopedia Cross-Reference
Agency — Special Agency Doctrines (Subagents, Power of Attorney), The Law Mind Business Organizations & Corporate Law Encyclopedia