## Facts

- In 1952, six-year-old Frances McLaughlin nearly drowned in a New Hampshire lake and was pulled from the water unconscious.
- Volunteer firefighters arrived with emergency equipment, including “M-S-A Redi-Heat Blocks,” small magnesium heat-generating blocks packaged and distributed by Mine Safety Appliances Co. (MSA) for emergency use.
- The blocks were covered with red wool-like material; tests showed they quickly reached surface temperatures around 200°F and remained hot for an extended time.
- The container displayed promotional language (e.g., “ALWAYS READY FOR USE” and “ENTIRELY SELF CONTAINED”); directions in smaller print stated that the activated block should be wrapped in an insulating medium (e.g., towel, blanket, folded cloth).
- Firefighters activated the blocks and handed them to a woman who identified herself as a nurse; she placed several blocks directly on the child’s body under blankets.
- The child later developed blisters and was diagnosed with third-degree burns, requiring substantial hospital treatment.
- Trial evidence included testimony that a fireman previously received instruction that the blocks had to be insulated; he claimed he warned the nurse, but the nurse and a family member testified they did not hear a warning.
- The fireman watched the nurse apply the blocks directly to the child and did not intervene.

## Issues

1. Whether MSA, as packager/distributor, had a duty to provide adequate warnings of the blocks’ latent burn risk to end users and whether its warnings were sufficient under applicable substantive law.
2. Whether the fireman’s knowledge and failure to ensure insulation (including any failure to warn or prevent misuse) could constitute an intervening, superseding cause breaking the causal chain from any inadequacy in MSA’s warnings.
3. Whether the trial court’s jury instructions properly explained foreseeability and intervening/superseding cause in assessing proximate cause.

## Decision

- The New York Court of Appeals reversed the judgment for plaintiffs and ordered a new trial.
- The court held that the jury charge on proximate cause and intervening negligence was erroneous because it did not adequately frame the jury’s task in deciding whether the fireman’s conduct could be a superseding cause.
- The court did not resolve liability as a matter of law; it required retrial with correct instructions so the jury could decide negligence and causation.

## Legal Principles

- In failure-to-warn cases involving latent dangers, a seller or distributor may have a duty to give warnings sufficient to alert users to concealed risks and safe-use requirements.
- Proximate cause may be cut off by a third party’s intervening act when that act is independent and not reasonably foreseeable, and when it becomes the immediate cause of the injury.
- When an intermediary has actual knowledge of the danger and a realistic opportunity to prevent misuse, the intermediary’s failure to warn or prevent harm may be found by the factfinder to supersede an earlier failure to warn by the product’s seller/distributor.
- Where the intervening/superseding-cause issue is central to the case, the jury must be instructed in a way that clearly permits it to decide whether the third party’s conduct broke the causal chain.

## Conclusion

The court ordered a new trial because the jury was not properly instructed on whether the fireman’s knowledgeable failure to ensure insulation of the heat blocks could be an intervening, superseding cause that would relieve the distributor of liability for any inadequacy in its warnings.


McLaughlin v. Mine Safety Appliances Co., 11 N.Y.2d 62 (N.Y. 1962)