Halliburton Energy Services Inc v Smith International (North Sea) Ltd & Ors

A patent provides a sufficient enabling disclosure only where the skilled addressee can perform the invention without undue effort. Routine work may become excessive because of its scale or duration. The assessment is one of degree and judgment. Relevant matters include the nature and technological field of the invention, the work required, the width of the claim and any functional limitations.

Essential information omitted from the specification may be obtained from another document only where the patent gives a clear and unambiguous direction to it. A reference appearing merely in the description of the prior art does not ordinarily incorporate that document's teaching.

The patentee sued three related companies for infringement of two patents concerning rotary cone drill bits. The defendants counterclaimed for revocation. Pumfrey J held that some accused products fell within the claims but revoked both patents for insufficiency: [2005] EWHC 1623 (Pat); [2006] RPC 25.

After settlement, the patentee continued its appeal concerning the Force Balancing Patent. The Comptroller General of Patents assisted the court because the respondents no longer participated. The appeal challenged the legal approach to sufficiency and the assessment of whether the specification enabled a skilled team to construct the computer simulation needed to design a force-balanced drill bit.

1. Appeal dismissed. The judge was entitled to find the Force Balancing Patent insufficient. Sufficiency required the specification to enable the skilled addressee to perform the invention without undue effort. The amount and duration of routine work remained relevant. A gigantic project could fail that requirement even where its individual steps involved no invention.

2. The assessment was one of degree and judgment. It required consideration of all relevant circumstances, including the nature and technological field of the invention, the width of the claim and any functional limitations. The European Patent Office's undue-effort approach was apposite and had general application. The extreme submission that timescale was legally irrelevant was rejected.

3. Where the skilled addressee was a multidisciplinary team, the law did not appoint one member as its head. Each notional member contributed within that member's own expertise. The relevant team for sufficiency and obviousness had to possess the same characteristics, including any willingness to undertake an immense amount of work.

4. The judge's evaluation disclosed no error of principle. Constructing the necessary kinematic model required extraordinary work, including work comparable to that underlying an original peer-reviewed scientific paper. The specification supplied virtually no adequate instruction for determining the essential cone-to-bit speed relationship. Its force model also rested on an incorrect assumption that force was linearly proportional to penetration depth. Once that fundamental assumption was shown to be wrong, the evidential burden lay on the person asserting that the resulting model nevertheless produced useful results.

5. Essential information outside a patent forms part of its enabling disclosure only where the skilled reader receives a clear and unambiguous direction to obtain it. The patent's references to the Ma paper merely described background prior art and did not incorporate its teaching. The specification therefore could not be supplemented by that paper.

6. The court granted permission concerning the volume-matrix factual issue because the judge had erred on that point. That error did not affect the remaining, independently sufficient grounds of invalidity. Permission concerning calculation of forces on a tooth was refused because no realistic prospect of success existed.

1. Court of Appeal (Civil Division): Dismissed the appeal and upheld revocation of the Force Balancing Patent for insufficiency: [2006] EWCA Civ 1715.
2. High Court, Patents Court: Pumfrey J held that some accused drill bits fell within the patent claims but revoked both patents for insufficiency: [2005] EWHC 1623 (Pat); [2006] RPC 25.