## Facts

- Timothy Diehl worked for IA Construction, Inc. on a road-construction crew using a Blaw-Knox “road widener” manufactured in 1970.
- The road widener deposited and spread material along the roadside and was typically followed closely by laborers performing cleanup and leveling tasks.
- On May 24, 1999, Diehl walked behind the road widener when it stopped and then reversed; unaware it was backing up, he was within a few feet and his legs were trapped under the rear wheels, causing severe injuries.
- Diehl and his wife sued the manufacturer and related entities under Pennsylvania products-liability law, alleging defective design and inadequate warnings because the machine had unenclosed rear wheels, lacked a rear back-up alarm, and lacked adequate warning signs.
- After the accident, IA (a non-party) modified the machine by partially enclosing the rear wheels, installing a rear back-up alarm, and placing rear warning signs to prevent similar accidents.
- Plaintiffs sought to introduce evidence of IA’s post-accident modifications to show defectiveness and feasible safer alternatives.

## Issues

1. Whether Federal Rule of Evidence 407 bars evidence of subsequent remedial measures taken by a non-party when offered to prove a product defect, design defect, or need for warnings.
2. Whether the evidence was nonetheless excludable under Federal Rule of Evidence 403 for risk of confusion or unfair prejudice.
3. Whether excluding the evidence, if erroneous, was harmless in light of the defense verdict.

## Decision

- The Third Circuit held Rule 407 does not bar evidence of remedial measures taken by a non-party.
- The court concluded IA’s modifications were relevant to defect and feasibility and were not properly excluded under Rule 403.
- The court found the exclusion was not harmless because the evidence bore directly on the central disputed design-safety issues.
- The judgment for Blaw-Knox was reversed and the case remanded for a new trial.

## Legal Principles

- Federal Rule of Evidence 407’s exclusion for subsequent remedial measures applies to measures taken by a party, not a non-party.
- The policy of encouraging defendants to make safety improvements does not justify excluding remedial measures undertaken by third parties, which would otherwise create an unwarranted evidentiary benefit for defendants.
- Evidence of non-party post-incident modifications may be admissible to prove product defect, design defect, feasibility of safety measures, or need for warnings, subject to ordinary relevance and Rule 403 limits.
- Potential juror confusion about who made the changes generally can be addressed through limiting instructions and clear attribution, rather than categorical exclusion.
- Erroneous exclusion of highly probative evidence is reversible when it likely affected the verdict on contested elements central to the case.

## Conclusion

The Third Circuit ordered a new trial after holding that Rule 407 does not exclude subsequent remedial measures taken by a non-party and that excluding the employer’s post-accident safety modifications—highly probative of design defect and feasibility—was an evidentiary error that likely influenced the jury’s verdict.


Diehl v. Blaw-Knox, 360 F.3d 426 (3d Cir. 2004)