Defences (consent, contributory negligence, illegality)

TOR.09 — Defences: Consent, Contributory Negligence, Illegality

Consent (volenti non fit injuria)

A complete defence. Claimant must have (1) full knowledge of the nature and extent of the risk, and (2) voluntarily agreed to accept it (run the risk and waive the legal claim). Mere knowledge is not consent — Smith v Baker.

• Tests/cases: Morris v Murray (drunk pilot — passenger volens). Dann v Hamilton (getting into car with drunk driver = knowledge, not consent).
• Rescuers are not volenti — Haynes v Harwood, Baker v Hopkins.
• Road traffic: RTA 1988 s.149 bars volenti against a passenger where compulsory insurance applies — a key trap.
• Employees: courts reluctant to find true consent (Smith v Baker).
• For occupiers, OLA 1957 s.2(5) / OLA 1984 s.1(6) preserve volenti for risks willingly accepted.

Contributory Negligence

A partial defence — reduces damages, does not defeat the claim. Law Reform (Contributory Negligence) Act 1945 s.1(1): damages reduced "to such extent as the court thinks just and equitable" having regard to the claimant's share in responsibility.

• Two elements: claimant failed to take reasonable care for own safety, and that fault contributed to the damage (not necessarily to the accident) — Froom v Butcher (seatbelts: 25% / 15% / 0% guideline).
• Children: standard is that of an ordinary child of the same age — Gough v Thorne.
• Emergency/agony of the moment: judged leniently — Jones v Boyce.
• 100% reduction is not permitted (Pitts v Hunt) — it would contradict the finding of defendant liability.

Illegality (ex turpi causa non oritur actio)

A complete defence where the claim arises from the claimant's own illegal/immoral act.

• Leading test: Patel v Mirza [2016] UKSC — a trio of considerations: (a) the underlying purpose of the prohibition transgressed; (b) other relevant public policy that might be denied by refusing the claim; (c) proportionality of denying the claim against the wrongdoing. This replaced the old rigid "reliance" test.
• Applied in tort: Henderson v Dorset Healthcare (UKSC 2020) — barred where claim founded on the claimant's own serious criminal act (manslaughter).

Common traps

• Complete vs partial: consent and illegality defeat the claim; contributory negligence only reduces.
• Volenti needs agreement, not mere awareness; RTA s.149 defeats it against passengers.
• No 100% contributory reduction.
• Use the Patel v Mirza trio for illegality — not the abolished reliance test.