## Facts

- Paul A. Babcock III drove a General Motors pickup truck that left the road and struck a tree, causing catastrophic injuries that later led to his death.
- The estate alleged a design defect in GM’s “Type I” seat belt buckle, claiming crash forces caused an “inertial unlatch” that released the belt during impact.
- Because Babcock could not testify, the estate sought to prove he was belted through lay testimony that he consistently wore a seat belt whenever in a vehicle.
- Multiple witnesses testified they had ridden with Babcock on many occasions (about thirty or more) and that he wore a seat belt each time.
- The estate also offered expert testimony that the buckle design could unlatch under crash forces without intentional activation of the release button.
- GM disputed that Babcock was wearing the belt and challenged the defect and inertial-unlatch theory.
- In a diversity action in the District of Maine, the court admitted the habit and expert evidence; a jury found for the estate on negligence and strict products liability.

## Issues

1. Whether testimony that Babcock “always” wore a seat belt was admissible as habit evidence under Federal Rule of Evidence 406 rather than inadmissible character evidence.
2. Whether the trial court abused its discretion in admitting expert testimony supporting the inertial-unlatch defect theory.
3. Whether the evidence of defect and causation was sufficient to support the verdict, and whether alleged instructional and trial errors required reversal.

## Decision

- The First Circuit affirmed the judgment for the estate.
- The court held the seat-belt-use testimony was properly admitted as habit evidence under Rule 406.
- The court held the admission of expert testimony on inertial unlatching and defect was within the trial court’s discretion.
- The court concluded the combined habit, expert, and circumstantial evidence permitted a reasonable jury to find defect and causation.
- The court rejected GM’s remaining claims of prejudicial trial error, including challenges to jury instructions.

## Legal Principles

- Under Federal Rule of Evidence 406, evidence of a person’s habit is admissible to prove conduct on a particular occasion conformed to that habit.
- Habit requires regular, specific, repeated conduct in response to a particular situation; it is distinct from generalized character evidence.
- Trial courts have broad discretion over evidentiary rulings, including the admission of expert testimony; appellate review is for abuse of discretion.
- In products-liability cases, defect and causation may be proven by circumstantial evidence combined with admissible habit and expert testimony; direct proof is not required if the jury can reasonably infer causation.

## Conclusion

The First Circuit upheld a jury verdict against GM, ruling that consistent seat-belt-use testimony qualified as Rule 406 habit evidence and that the trial court permissibly admitted expert and circumstantial proof supporting a buckle-defect and inertial-unlatch causation theory.


Babcock v. Gen. Motors Corp., 299 F.3d 60 (1st Cir. 2002)