## Facts

- Carl D. Clay (inventor) and Marathon Oil Co. (assignee) sought patent claims for a process to store refined liquid hydrocarbons in a tank with a “dead volume” below the outlet port where product can stagnate and degrade.
- The claimed process places a gelation solution into the dead volume and allows it to gel in situ, displacing unusable space and raising the effective liquid level toward the outlet.
- The examiner rejected the claims as obvious under 35 U.S.C. § 103 based on combining two references:
  - A storage-tank reference teaching displacement of bottom volume using inflexible bladders.
  - An oil-recovery reference teaching injection of gels into subterranean formations to plug high-permeability channels and improve crude oil production.
- The Board of Patent Appeals and Interferences affirmed, treating the subterranean gel reference as analogous art and combining it with the storage-tank reference.
- Clay appealed, arguing the subterranean gel reference was non-analogous art and could not be used in the obviousness analysis.

## Issues

1. What is the governing test for whether a prior-art reference is “analogous art” for purposes of an obviousness analysis under 35 U.S.C. § 103?
2. Under that test, whether a reference about injecting gels into subterranean formations for oil recovery is analogous to a claimed method using gel in a storage tank to eliminate dead volume.

## Decision

- The Federal Circuit reversed the Board’s decision sustaining the § 103 rejection.
- The court held the subterranean gel reference was non-analogous art because it was neither in the same field of endeavor nor reasonably pertinent to the problem addressed by the claimed invention.
- Because the obviousness rejection depended on combining the storage-tank reference with the non-analogous gel reference, the Board’s obviousness conclusion was clearly erroneous on this record.

## Legal Principles

- A prior-art reference is analogous if it is either (1) from the same field of endeavor as the claimed invention (regardless of the problem addressed), or (2) reasonably pertinent to the particular problem the inventor was trying to solve.
- “Same field of endeavor” is not established merely because both the reference and the invention relate broadly to the same industry; the relevant comparison is the technological area and use context.
- A reference is “reasonably pertinent” only if, due to the problems addressed, it would logically have commended itself to a person of ordinary skill seeking to solve the inventor’s problem.
- Non-analogous art cannot properly be combined to supply a missing claim element in a § 103 analysis.

## Conclusion

The court set aside the PTO’s obviousness rejection because the cited gel technology for subterranean oil recovery was too remote from the field and problem of storage-tank dead volume, and thus could not be used as analogous art to justify combining references under § 103.


In re Clay, 966 F.2d 656 (Fed. Cir. 1992)