ICI v Shatwell [1965] AC 656 (House of Lords)
Basic Facts: G and J, shot firers at a quarry, ignored safety instructions and tested detonators in an unsafe manner, resulting in an explosion that injured J. J sued for the injuries.
Issue: What constitutes an agreement for the purposes of volenti non fit injuria (consent to the risk of harm)?
Held: D was not liable for any damages. C had voluntarily assumed the risk of injury.
Lord Reid: There is a difference between careless collaboration and deliberate disobedience. In this case, the latter applies, making volenti non fit injuria a complete defense since both parties consented to the risk.
Lord Pearce: The defense applies if there was a genuine, pressure-free agreement to assume the risk. Here, it was implied that G would not sue J for injuries, making volenti applicable.