Geofabrics Ltd v Fiberweb Geosynthetics Ltd

Patent claims are construed purposively through the eyes of the skilled addressee and in the context of the invention. A requirement that a filtration layer be “normally impermeable” is not an absolute requirement that no water ever passes through it. In a railway trackbed, normal conditions include the ballast, sleepers and rails, rainwater, and the practical conditions of use, but exclude unusual flooding.

A claimed pore size is not implied where the claim contains functional requirements and narrower subsidiary claims specify dimensions. Novelty requires clear directions that inevitably result in the claimed invention. Obviousness is assessed by the statutory test, disciplined by the Pozzoli steps. A product patent need not explain the complete physical theory of operation if the invention can be made and tested without undue burden.

Geofabrics sued Fiberweb for infringement of European Patent (UK) 2 430 238, concerning a trackbed liner intended to prevent pumping erosion while permitting water to pass upwardly under train loading. Fiberweb denied infringement and counterclaimed for revocation for lack of novelty, obviousness and insufficiency.

The prior art relied on was Hoare, including its reference to Gore, and Jay. The principal issues were the construction of the patent, whether the prior art anticipated or rendered it obvious, whether the specification was insufficient, and whether Fiberweb’s Hydrotex product fell within the claims.

1. Construction. “Normally impermeable to liquid water” meant impermeable in normal railway-trackbed conditions, not absolutely impermeable. Normal conditions included the weight of the ballast, sleepers and rails and ordinary rainwater, but not unusual flooding. The claim did not imply a maximum pore size of 2µm; that limitation appeared only in narrower claims.
2. Novelty. Hoare, even incorporating Gore, did not disclose a filtration layer which was normally impermeable but permitted upward passage of water under train loading while restricting solids. It did not give clear directions which inevitably resulted in the claimed invention. The novelty attack therefore failed.
3. Obviousness. Applying the Pozzoli approach, the skilled addressee would need to depart materially from Hoare and Jay. Hoare taught a substantially impermeable intermediate layer. Jay likewise relied on impermeability and did not suggest introducing a filtering layer operating only under train load. The required modifications were not obvious. A reasonable expectation of success, rather than certainty, was required for an obvious-to-try argument. Long-felt want was relevant but was not a stand-alone answer to obviousness.
4. Insufficiency. The claims were not uncertain. The skilled addressee could determine the boundary of the invention in its practical industrial context. The patent did not need to disclose a complete scientific theory of the mechanism. Hydrotex had been shown to work and could be tested without undue burden. The plausibility attack also failed.
5. Infringement. Hydrotex operated by filtering slurry under train loading. Localised “bathtub” areas did not prevent it from being normally impermeable. Hydrotex therefore infringed. Alternatively, the product would have infringed by equivalence: it achieved substantially the same result in substantially the same way, and strict literal compliance was not shown to be essential.

The patent was not anticipated, was not obvious over Hoare, Gore or Jay, and was not insufficient. Hydrotex infringed.

First-instance decision. No appellate history was stated in the judgment.