Fiberweb Geosynthetics Ltd v Geofabrics Ltd

Factual and Procedural Background

This appeal arises from an order dated 9 April 2020 made by Judge Stone sitting as a Deputy High Court Judge, following his judgment on 5 March 2020, in which he held that European Patent (UK) No. 2 430 238 ("the Patent") owned by the Plaintiff was valid and infringed by the Defendant. The Defendant was granted permission to appeal on two grounds: first, that the judge erred in construing claim 1 of the Patent, leading to an incorrect finding of infringement by the Defendant's Hydrotex 2.0 product; and second, that the judge erred in concluding that claim 1 was novel over International Patent Application No. WO 95/04190 ("Hoare"). Permission to appeal was refused on the Defendant's alternative contention of obviousness over Hoare.

The technical background involves the construction of railway trackbeds, typically comprising layers of ballast over varying subgrade soils, including clay-rich soils prone to pumping erosion caused by repeated train loads. The Patent concerns a synthetic trackbed liner designed to mitigate pumping erosion by permitting controlled upward passage of water under dynamic train loads while restricting solids passage.

Legal Issues Presented

1. Whether the judge erred in the purposive construction of claim 1 of the Patent, particularly the interpretation of the term "normally impermeable to liquid water" in the absence of a vehicle load.
2. Whether claim 1 of the Patent lacks novelty over the prior art disclosed in International Patent Application No. WO 95/04190 ("Hoare").

Arguments of the Parties

Defendant's Arguments

• The judge's construction of claim 1 was incorrect; "normally impermeable" should mean impermeability under a water pressure equivalent to the static load of track, sleepers, and ballast (approximately 2.9kN/m²).
• The prior art document Hoare, including its cross-reference to the Gore patent, anticipates claim 1 by disclosing a similar multi-layer structure with a filtration layer that is water vapor permeable but substantially impermeable to liquid water.
• The judge wrongly focused on impermeability to water above the filtration layer, whereas the relevant consideration is impermeability to water below the filtration layer (i.e., water in the subgrade) in the absence of a train load.
• The judge disregarded relevant teachings of the specification and improperly relied on physics not explicitly included in the specification or agreed common general knowledge.

Plaintiff's Arguments

• The claim must be interpreted purposively as defined within the claim and specification, with "normally impermeable" meaning impermeable to liquid water absent the dynamic load of a vehicle but not requiring absolute impermeability under all conditions.
• Hoare does not disclose or direct the skilled person to a filter layer that is normally impermeable but becomes permeable under load as claimed; it lacks an individualised description of the claimed invention.
• The cross-reference to Gore in Hoare is to the general method of making materials, not to any specific example that meets the Patent's criteria.
• The judge’s construction accords with the physics of the situation and the common general knowledge of the skilled person.

Table of Precedents Cited

Court's Reasoning and Analysis

The court first addressed the construction of claim 1, focusing on integer 1.4, which defines the filtration layer as "normally impermeable to liquid water" absent the load of a vehicle. It emphasized purposive construction, referencing the definition within the claim and specification that "normally impermeable" means impermeable in normal conditions without a train load, but not requiring absolute impermeability under exceptional conditions such as floods.

The court rejected the Defendant's argument that "normally impermeable" requires impermeability under static water pressure equivalent to the load of track, sleepers, and ballast (about 2.9kN/m²). It distinguished between static load and dynamic load during train passage, noting that the dynamic load causes transient hydrostatic pressure that influences permeability. The court found that the Defendant conflated these concepts and that the specification's references to static and dynamic loads were sufficiently clear to support the Plaintiff's construction.

The court accepted expert evidence explaining the physics of water movement and pressure in the subgrade and ballast, concluding that the judge's construction was essentially correct.

Regarding infringement, the court noted experimental evidence on the Defendant's Hydrotex product showing water entry pressure (WEP) between 0.5kPa and 2.7kPa, with both parties agreeing that a water head greater than 50mm is exceptional and not normal. Therefore, Hydrotex falls within the scope of claim 1 as construed, supporting the finding of infringement if the Patent is valid.

On novelty, the court examined Hoare and its cross-reference to Gore. It found that Hoare does not disclose a filtration layer that is normally impermeable but becomes permeable under train load, nor does it provide clear instructions that inevitably result in the claimed invention. The reference to Gore was to a general method, not to any specific example such as Gore's example 10, which alone might meet the criteria.

The court applied established principles distinguishing novelty from obviousness, emphasizing that prior art must necessarily anticipate the invention, not merely make it obvious. It found that Hoare, even with Gore, does not anticipate the Patent, rejecting the Defendant's novelty challenge.

Holding and Implications

The court DISMISSED the Defendant's appeal.

The direct effect is that the judgment below, holding the Patent valid and infringed by the Defendant's Hydrotex product, stands. No new precedent was established beyond the application of settled principles of claim construction, novelty, and infringement to the facts of this case.