Saint-Gobain PAM SA v Fusion Provida Ltd & Anor

Factual and Procedural Background

This appeal arises from a judgment given by Judge Pumfrey on 3rd November 2004 concerning the validity of European Patent (UK) No 0686246. The sole issue before the judge was whether the patent was invalid due to obviousness. It was accepted that if the patent was valid, the defendants infringed it. The judge held the patent valid and found infringement accordingly. The patentees, represented by Attorney Wilson QC, are Company A, a large manufacturer of underground pipes typically used for sewage or water supply. The defendants are a smaller company operating in the same industry. The priority date of the patent is 18th February 1993, and the dispute centers on whether claim 1 is obvious in light of a prior disclosure known as Johnsson, published shortly before the priority date.

Legal Issues Presented

1. Whether claim 1 of the patent is obvious in light of the prior art disclosure Johnsson and the common general knowledge of the skilled person in the underground pipe manufacturing field.

Arguments of the Parties

Appellant's Arguments

• The judge erred by allowing "historical considerations" to influence his decision, given that Johnsson was published just before the priority date, leaving no room for such considerations.
• Aside from the historical considerations, the case is a straightforward substitution of one protective coating (Zn/Al alloy) for another (Zn alone), as suggested by Johnsson, rendering the patent obvious.
• Relied on the appellate caution principle from Biogen v Medeva but argued the judge made an elementary error in principle.

Appellee's Arguments

• Johnsson added little to the common general knowledge already possessed by the skilled person.
• The special protective effects of the Zn corrosion product layer, including the "healing" effect and trapping by Al, were not disclosed in Johnsson.
• Maintained that the judge correctly considered the evidence and that the invention was not obvious despite the prior art.
• Supported position with a Respondent's notice detailing these points.

Table of Precedents Cited

Precedent	Rule or Principle Cited For	Application by the Court
Windsurfing v Tabur Marine [1985] RPC 59	Framework for assessing obviousness via four-step test.	The court applied the Windsurfing steps to identify the inventive concept, common general knowledge, differences with prior art, and whether differences were obvious.
Biogen v Medeva [1997] RPC 1	Appellate caution in overturning factual findings and evaluation of obviousness.	The court emphasized deference to the judge's overall evaluation and cautioned against re-evaluating facts de novo on appeal.
Johns-Manville's Patent [1967] RPC 479	Obvious to try test where likelihood of success is sufficiently high to warrant trial.	The court distinguished this case from Johns-Manville, holding that there was no sufficient likelihood of success to render the invention obvious.

Court's Reasoning and Analysis

The court began by identifying the inventive concept as the substitution of a Zn/Al alloy coating for a Zn coating on buried iron-based pipes. The common general knowledge included the properties and protective mechanisms of Zn coatings in buried pipes, including the formation of a protective corrosion product layer ("white rust") that protects damaged areas.

The court acknowledged that Johnsson disclosed the use of Zn/Al alloy coatings for steel in soil but noted it lacked any reference to the critical protective corrosion product layer or the "healing" effect important for buried pipes. Moreover, Johnsson did not test pipes or coatings with the pore-sealing layer described in the patent.

The court emphasized that the skilled person would not have found it self-evident that the Zn/Al alloy would provide the same or better long-term protection as Zn alone, particularly given the importance of the corrosion product layer and the complex, unpredictable nature of soil corrosion. Expert evidence confirmed the unpredictability of corrosion behavior and the absence of scientific understanding sufficient to justify a confident expectation of success.

The court rejected the appellant's argument that the invention was obvious to try, noting that the "obvious to try" principle requires a reasonable expectation of success, which was lacking here.

Applying the appellate caution principle from Biogen v Medeva, the court found no error of principle in the judge's conclusion on obviousness, including his consideration of historical factors explaining why the substitution was not previously made despite long-standing common general knowledge.

Accordingly, the court upheld the judge's finding that the patent was valid and not obvious.

Holding and Implications

DISMISSED

The court dismissed the appeal, affirming the validity of the patent. The appellant was ordered to pay the respondent's costs of the appeal. Permission to appeal to the House of Lords was refused. No new precedent was established; the decision confirms the application of established principles on obviousness and appellate review in patent cases involving complex technical evidence and the importance of the skilled person's common general knowledge and inventive concept.