## Facts

- In 1977, Florence Vassallo received silicone-gel breast implants manufactured by Heyer-Schulte Corporation.
- Through later corporate transactions, Baxter became responsible for liabilities tied to those implants.
- In 1992, imaging suggested one implant had ruptured and the other had multiple pinholes allowing silicone gel to escape.
- During explant surgery in 1993, the surgeon observed encapsulation in scar tissue, permanent scarring on pectoral muscles, and silicone granulomas.
- Vassallo claimed gel leakage caused chronic inflammation, permanent tissue scarring, and immune-system problems; she testified she would have declined implantation with adequate risk information.
- Trial evidence supported that, by 1977, the manufacturer knew implant durability varied and did not adequately warn about gel migration and related complications.

## Issues

1. Whether expert testimony on general and specific causation was admissible under the Lanigan reliability standard despite limited epidemiological support.
2. Whether failure-to-warn liability under the implied warranty of merchantability should be limited to risks reasonably foreseeable or discoverable by reasonable testing at the time of sale, rather than judged by hindsight.
3. Whether the trial court committed reversible error in admitting evidence offered to show notice and product safety (including third-party complaints and internal research documents) and in limiting experts’ reliance on out-of-court opinions.
4. Whether jury instructions on design defect improperly treated failure to test as an independent basis of liability.

## Decision

- The court affirmed the judgments for the plaintiffs on negligence, breach of implied warranty (including failure to warn), and the statutory consumer-protection claim.
- The court held the causation experts were properly admitted because the judge could find their reasoning and methods scientifically valid under Lanigan; challenges went to weight, not admissibility.
- The court revised Massachusetts law on failure-to-warn claims under implied warranty, rejecting strict hindsight liability for unknowable risks and adopting a knowable-risk standard tied to reasonable foreseeability and reasonable testing at the time of sale.
- Applying the revised standard, the court concluded evidence permitted a finding that the manufacturer had actual or constructive knowledge of relevant risks in 1977 and failed to provide adequate warnings.
- The court upheld key evidentiary rulings admitting notice-related materials with limiting instructions and restricting experts from repeating out-of-court scientific opinions as hearsay.
- The court upheld the design-defect instructions allowing failure-to-test evidence to be considered as part of the defect analysis; any instructional error was not prejudicial on the full record.

## Legal Principles

- Scientific expert testimony is admissible if the proponent shows, under Lanigan, that the opinion rests on reliable principles and methods reliably applied; epidemiological proof is not a prerequisite.
- In implied-warranty failure-to-warn claims, a manufacturer is not liable for failing to warn about risks that were not reasonably foreseeable at the time of sale or could not have been discovered by reasonable premarketing testing.
- A manufacturer has a duty to conduct reasonable safety testing before marketing and to warn about risks that such testing would reveal.
- The duty to warn is continuing; warnings must be updated when risks become known after sale.
- Notice evidence (including complaints and internal research materials) may be admitted for limited purposes, with instructions limiting improper use as proof of the truth of the matters asserted.

## Conclusion

The court upheld verdicts arising from injuries attributed to leaking silicone breast implants, approved a flexible reliability approach to scientific causation evidence, and recalibrated Massachusetts failure-to-warn warranty doctrine to require that the risk be knowable through reasonable foresight or testing at the time of sale, while maintaining a continuing post-sale duty to warn.


Vassallo v. Baxter Healthcare Corp., 428 Mass. 1 (1998)