Restraint of trade

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Restraint of trade: a simple guide

What it is
Restraint of trade is a traditional common‑law idea about how freely people and businesses can work. It tries to protect legitimate interests (like trade secrets, customer relationships, or the value of a business) while avoiding unfair limits on competition. A contract that stops someone from trading is usually void unless the restriction is reasonable and tied to a legitimate purpose.

Two kinds of restraints
- Naked restraints: These try to stop someone from trading altogether or in a very broad way. They are generally not allowed.
- Ancillary restraints: These are restraints that accompany a legitimate contract (for example, a non‑compete clause tied to selling a business or to a lease). They can be allowed if they are reasonable and narrowly fit the purpose.

The rule of reason
Courts use a “rule of reason” test: is the restraint necessary and reasonable to achieve a legit purpose, and does its benefit outweigh any harm to competition or public policy? If yes, it may be upheld; if not, it’s likely invalid.

History in brief
- Mitchel v Reynolds (1711): A trader may regulate how they run a business, but restraints must be reasonable and lawful.
- Nordenfelt v Maxim (1894): A promise not to compete everywhere in the world is often too broad; restraints should be reasonable in scope.
- Dyer’s Case: Restraints need some consideration (something of value in return).
- United States developments: early cases like Addyston Pipe & Steel Co. and Standard Oil applied the rule of reason to distinguish reasonable, ancillary restraints from naked restraints that unduly restrain trade. Over time, courts consider whether restraints are necessary, and if less restrictive means could achieve the same goal.

Restraining workers
In English law, non‑compete clauses in employment can be enforceable if:
- there is a legitimate business interest to protect (such as protecting customer connections or confidential information), and
- the restraint is reasonable in scope and duration. If a clause is too broad, it can be struck down or narrowed (the blue pencil principle).

Contemporary use
Today, modern competition laws in many countries limit restraints on trade. The restraint doctrine remains important, especially for post‑employment covenants and for certain business sale or collaboration agreements in the United States and other jurisdictions.

Bottom line
Restraint of trade tries to balance two goals: allow reasonable protections for legitimate business interests, and keep markets open and competitive. Restraints that are necessary and proportionate may be allowed; those that are too broad or harmful to public welfare are usually rejected.