## Facts

- Richard Tackett had serious, long-term knee problems and underwent right-knee surgery in 1988 and left-knee surgery in 1991; treating sources described severe degeneration and anticipated future joint replacements.
- In September 1991, Tackett fell at work, after which his knee condition worsened and he could no longer continue working as a machinist.
- In 1994, he attempted to work at a hardware store but quit after about a month because knee pain and functional limits prevented him from doing the job.
- Tackett applied for Social Security disability insurance benefits in 1993, alleging disability beginning in September 1991; the agency denied the claim initially and on reconsideration.
- Tackett requested and received a hearing before an administrative law judge (ALJ).
- Medical evidence, including the views of Tackett’s physicians and the ALJ’s medical experts, generally agreed Tackett could do at most sedentary work but needed to change positions and walk periodically—about every half hour.
- The ALJ found Tackett became disabled as of his 50th birthday (February 7, 1995) but was not disabled from September 16, 1991 through February 6, 1995, finding he could work eight-hour shifts with breaks every two hours.
- For the pre-age-50 period, the ALJ did not call a vocational expert and relied exclusively on the Medical–Vocational Guidelines (the “grids”) to find Tackett not disabled.
- The Appeals Council denied review, and the district court affirmed the denial of benefits for the pre-age-50 period; Tackett appealed to the Ninth Circuit.

## Issues

1. Whether the Commissioner met the step-five burden to show Tackett could perform other work existing in significant numbers during September 16, 1991 to February 6, 1995.
2. Whether the ALJ could deny benefits for that period by relying solely on the grids, without vocational evidence, despite Tackett’s nonexertional limitations requiring frequent position changes and periodic walking.

## Decision

- The Ninth Circuit reversed the district court’s judgment affirming the denial of benefits for the closed period and remanded.
- The court held the ALJ erred at step five by relying exclusively on the grids even though Tackett’s nonexertional limitations significantly limited the range of sedentary work available.
- Because the ALJ did not obtain vocational-expert testimony (or similar evidence) identifying jobs Tackett could perform with his limitations, the Commissioner failed to carry the step-five burden for the disputed period.

## Legal Principles

- Disability claims are evaluated under a five-step sequence; once a claimant shows he cannot perform past relevant work, the burden shifts at step five to the Commissioner to show other work exists in significant numbers in the national economy that the claimant can do.
- The grids may be used to meet the step-five burden only when they accurately describe the claimant’s functional capacity and limitations.
- The grids primarily account for exertional limits; when nonexertional limits significantly restrict the range of work a claimant can perform within an exertional category (such as sedentary work), exclusive reliance on the grids is improper.
- When nonexertional limits materially reduce the occupational base, the Commissioner generally must use additional evidence—commonly vocational-expert testimony—to identify specific jobs the claimant can perform and to show those jobs exist in significant numbers.

## Conclusion

Tackett v. Apfel held that the Commissioner could not deny benefits for Tackett’s pre-age-50 period by mechanically applying the grids where the medical record showed significant nonexertional limits (needing to change positions and walk frequently) that reduced the sedentary job base; without vocational evidence, the Commissioner did not meet the step-five burden, requiring reversal and remand.


Tackett v. Apfel, 180 F.3d 1094 (1999)