6. c. 28) is an Act of Parliament of the United Kingdom, which allows a judge to apportion liability for compensatory damages as he feels to be "just and equitable" between a tortfeasor and an injured person who was partly to blame.

This rule composed what is sometimes called the "unholy trinity" of defences to negligence which wrought particular hardship on 19th century workers, and barred them from any compensation for ghastly workplace injuries (the other two are common employment[1] and volenti non fit injuria).

An example is seen in The Wagon Mound (No 1) where the claimant conceded that a burning ship accident was unforeseeable in order to avoid the contemporary Australian contributory negligence bar.

This 1945 Act was not based on entirely new principles: the Collision Convention of 1910 had already provided that where two ships collide, blame may be apportioned between the two, so that each's contribution to the accident may be calculated to determine the settlement by way of damages.

In Froom v Butcher,[5][6] Lord Denning MR sliced the Gordian knot by declaring that such a passenger was NOT volenti but rather was 20% contributorily negligent in the matter.