Patents

Case Note: Horne Engineering Co. Ltd. v Reliance Water Controls Ltd.

John Lambert

10 Aug 1999
This article formerly appeared on the Lancaster Buildings website

It is trite law that a patent is to be given a purposive construction. However, it is not always clear what that means in practice. There is no doubt as to what should be the court's objective. The protocol on the interpretation of art 69 of the European Patent Convention, which governs the construction of British as well as European Patents by virtue of s. 125 (3) of the Patents Act 1977, mandates a construction "which combines a fair protection for the patentee with a reasonable degree of certainty for third parties." Difficulty arises when, as in this case, the words chosen by the patentee to delineate its claim are capable of several constructions at almost every point.
The Facts
The patent in suit was a thermostatic valve for controlling the temperature of running water for showers, hand basins and baths. The invention worked by admitting hot and cold water through a slide valve containing two ports so arranged that as one port opened the other one closed. The slide responded to a change in length of a temperature sensitive element so that an increase in water temperature caused
the hot port to close and the cold to open and vice versa. The defendant manufactured a range of thermostatic valves, which also employed a slide valve that responded to change of temperature and pressure. The patentee alleged that such arrangement infringed its claims. In response, the defendant counterclaimed for revocation of the grant on grounds of anticipation, obviousness and insufficiency.
Judgment

Pumfrey J held that the patent had not been infringed and that it was bad for obviousness and insufficiency. Applying Improver Corporation v Remington [1990] FSR 181, he considered how the invention worked. That was to be sought in the specification alone, which, in this case, disclosed a dedicated flow of cold water at one end of the temperature sensitive element which caused it to contract. It followed that a valve that operated in a different way would fall outside the patent. The defendant's
valve operated differently in that it did not respond to a cold flow at all and therefore fell outside the claim. Applying the same test for anticipation as is to be applied for infringement, the judge found that thermostatic valves made by the French company Vernet SA had not anticipated the claim.

However, he concluded that it would have been possible for a skilled man familiar with the Vernet valve to design something that would have fallen within the claim without the exercise of ingenuity. It followed that the invention was obvious at the priority date  "being a design according to established principles which involved no ingenuity, but had an advantage in fact."

Although a plea of insufficiency is usually inconsistent with a plea of obviousness it was not in this case because the specification failed to disclose the length of a vital component, namely a baffle tube. Without this direction it was possible to choose a baffle tube of the wrong length which would prevent the invention from working. In so far as the invention was not obvious, the specification gave insufficient directions for putting it into effect.

Amendment
The patentee applied to amend the specification under s.75 of the Patents Act 1977 which the defendant opposed on the ground that it would have disclosed additional matter and was obscure. The judge made it clear that he would have allowed the application but as even the amended claims would have been bad for obviousness and insufficiency the issue did not arise.

 

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