## Facts

- Dr. Sakharam D. Mahurkar developed a double-lumen hemodialysis catheter using joined semi-circular tubes merging into a single tapered tip, intended to improve on prior coaxial catheters.
- On March 8, 1982, Mahurkar filed a U.S. design application for a “Double Lumen Catheter” consisting essentially of drawings; the design application was later abandoned.
- Mahurkar later filed U.S. utility applications (October 1, 1984 and January 29, 1986) using the same figures and asserting entitlement to the 1982 filing date under 35 U.S.C. § 120; they issued as U.S. Patent Nos. 4,568,329 and 4,692,141.
- Mahurkar also obtained a Canadian industrial design patent (issued August 9, 1982) based on the same drawings with added text.
- Vas-Cath and a licensee sought declaratory judgments of noninfringement and invalidity; Mahurkar and a corporate defendant counterclaimed for infringement.
- Vas-Cath argued the utility patents could not claim the 1982 priority date because the earlier design filing lacked an adequate written description under 35 U.S.C. § 112 ¶ 1, making the 1982 Canadian patent prior art that anticipated the utility claims under § 102(b).
- The district court granted partial summary judgment that none of the asserted utility claims was entitled to the 1982 filing date and entered a Rule 54(b) judgment declaring the utility patents anticipated and invalid.

## Issues

1. Whether a prior U.S. design application consisting essentially of drawings can provide the written description required by 35 U.S.C. § 112 ¶ 1 to support later utility claims seeking priority under 35 U.S.C. § 120.
2. Whether the district court properly granted summary judgment that the earlier drawings did not describe the later-claimed dimensional relationships in the utility patents.

## Decision

- The Federal Circuit reversed the summary judgment of invalidity and remanded.
- The court held that drawings may, as a matter of law, satisfy the § 112 ¶ 1 written-description requirement.
- The court concluded the district court applied an incorrect and overly demanding legal standard for written description, including effectively requiring the drawings to exclude all other variations.
- The court emphasized written description is a question of fact focused on what a person skilled in the art would understand as of the filing date, making summary judgment improper where evidence created a genuine dispute.
- The court criticized the district court for not evaluating written description on a claim-by-claim basis.
- The court relied in part on unrebutted expert testimony that a skilled artisan could infer the claimed dimensional relationships from the drawings.

## Legal Principles

- For § 112 ¶ 1, the disclosure must show that, as of the filing date, the inventor was in possession of the invention as later claimed, judged from the viewpoint of a person skilled in the art at that time.
- “Written description” is not limited to words; drawings can convey structure and relationships sufficiently to satisfy § 112 ¶ 1.
- Written description compliance is a question of fact; summary judgment is inappropriate when record evidence (including expert testimony) creates a genuine dispute about what the original disclosure conveyed.
- Written description support must be assessed claim by claim; lack of support for some claims does not justify a blanket ruling as to all claims without individual analysis.
- In determining entitlement to an earlier filing date under § 120, the earlier application must provide § 112 ¶ 1 support for the later-claimed subject matter.

## Conclusion

The Federal Circuit held that drawings alone can satisfy the written-description requirement and reversed the summary judgment that invalidated Mahurkar’s catheter utility patents, remanding for claim-by-claim application of the proper § 112 and § 120 standards based on what skilled artisans would have understood at the earlier filing date.


Vas-Cath Inc. v. Mahurkar, 935 F.2d 1555 (Fed. Cir. 1991)