Quinn v Leathem [1901] AC 495
Conspiracy; inducing breach of contract; trade union
(250 words)
Facts
Leathem, a butcher, had employees who did not belong to the Belfast Butchers’ Association (BBA). After experiencing some difficulties, he asked for his employees to be admitted to the BBA. The BBA, for whom Quinn was the treasurer, put pressure on a customer not to buy Leathem’s meat and also called out one of his own employees.
Issues
Upon direction by the judge that they have to decide whether Quinn and his co-officers’ main motive was to injure Leathem’s interests, the jury found malicious conspiracy between Quinn and other BBA officers. The Irish Court of Appeal later affirmed their view. Quinn (alone) appealed. He argued that a violation of a legal right must be shown – a conduct that would have been actionable regardless of motive and whether conspiracy was present. In other words, he claimed that an act that is not in itself actionable will not be made actionable by the presence of a malicious motive.
Decision/Outcome
Dismissing Quinn’s appeal, the Court held that his conspiracy to wrongfully and maliciously induce Leathem’s own employees and customers to stop working for/buying from him was actionable upon proof of damage. While people may come together lawfully (even if this may result in injury to the interests of others), if such a get-together is solely for the malicious purpose of causing harm to another, it becomes unlawful. Any kind of violation of someone’s legal rights (whether contractual, tortious or other) that was knowingly committed and offers no explanation/justification is actionable in tort.
Updated 20 March 2026
This article accurately summarises the facts, issues, and outcome of Quinn v Leathem [1901] AC 495 as a matter of legal history. The case remains good law as a foundational authority on the tort of conspiracy and the principle that a combination to injure without justification can be actionable on proof of damage.
However, readers should be aware that the legal landscape surrounding trade union liability has been substantially altered by statute since 1901. The Trade Disputes Act 1906, and subsequently the Trade Union and Labour Relations (Consolidation) Act 1992 (as amended), provide significant immunities to trade unions and their members acting in contemplation or furtherance of a trade dispute. In practice, the direct application of Quinn v Leathem-style liability to trade union industrial action is now heavily qualified by statute. Students should therefore treat this case primarily as establishing common law principle, and study the statutory framework alongside it to understand the current legal position.
