Smith International Inc v Specialised Petroleum Services Group Ltd

Patent claims are construed by asking what the skilled person would understand the patentee to mean, giving particular weight to the language chosen in the claim. A filter must both permit fluid to pass and retain suspended particles; a mere catchment area or aperture is not necessarily a filter. For anticipation, the prior publication must give clear and unmistakable directions which inevitably result in the claimed invention. A possibility or signpost towards the invention is insufficient. On appellate review of a Patent Office decision, the question is whether the decision was wrong, allowing appropriate respect for evaluative judgments.

The claimant appealed, and the defendant cross-appealed, from a decision of the Divisional Director of the Patents Office acting for the Comptroller. The dispute concerned amended claims in a patent for a down-hole tool designed to collect debris and filter well fluid in an oil or gas well.

The Comptroller held that claim 1 lacked novelty, but that several other claims were novel and non-obvious. The claimant challenged the decisions upholding claims 8, 13, 14, 15, 17 and 23. The defendant challenged the finding against claim 1. The prior art relied upon was a junk catcher or sand trap disclosed in US Patent 3,316,971, referred to as D6.

1. Appeal and cross-appeal. The appeal concerning claim 1 was allowed and the Comptroller’s decision was set aside. The cross-appeal was dismissed. The remaining challenged claims were upheld.
2. Construction. Applying the approach in Kirin-Amgen Inc v Hoechst Marion Roussel Ltd [2005] RPC 9, the claim was construed by reference to what the skilled person would understand the chosen language to mean. The claim was not to be widened or narrowed by reference to prior art, consistently with Glaverbel S.A v British Coal [1995] RPC 255 and Beloit v Valmet (No 2) [1995] RPC 705.
3. A filter must, as a whole, allow fluid to pass while retaining suspended solid particles. An impermeable catchment device, or apertures which merely permit some particles to pass, is not thereby a filter. A junk catcher may also be a filter if it performs those filtering functions.
4. Claim 1 required fluid to bypass the filter in one direction and pass through the filter in the reverse direction. D6 did not contain a filter within that construction. Alternatively, if its relevant components were treated as a filter, the fluid did not bypass it in either direction. D6 therefore did not anticipate claim 1.
5. Following General Tire & Rubber Company v Firestone Tyre & Rubber Company Ltd [1972] RPC 457, anticipation required clear and unmistakable directions and inevitability, not a disclosure capable of being carried out in an infringing way. The purpose and operation of D6 meant that it did not satisfy that test. The reasoning in Hickman v Andrews [1983] RPC 147 supported the conclusion that an overlap in possible uses does not itself establish anticipation.
6. The objection to claim 17 based on lack of clarity failed. Words may have uncertain boundary cases without making a claim unclear. The added-matter objection also failed because an elongate, vertically disposed filter was disclosed and its advantages were apparent to the skilled person.
7. Claim 23 was a method claim. D6 did not disclose cleaning or filtering fluid while running the tool. Preventing debris from settling, or removing debris incidentally with the tool, did not amount to cleaning.
8. On appellate review under CPR Part 52, the relevant question was whether the Comptroller’s decision was wrong. The findings on obviousness were within the permissible range of evaluative judgment.

1. High Court (Chancery Division): appeal from the decision of the Divisional Director of the Patents Office acting on behalf of the Comptroller, dated 1 December 2004. The appeal was allowed on claim 1 and the cross-appeal was dismissed.