Patents

Case Note Playhut Inc. v Spring Form Inc. and others

John Lambert

25 Oct 1999
Last updated 15 Nov 2005

This article formerly appeared on the Lancaster Buildings website

This case considers two of the grounds on which a patent may be revoked, namely "added matter" under s. 72 (1) (d) of the Patents Act 1977 and "insufficiency" under s. 72 (1) (c). A patent may be revoked under s. 72 (1) (d) if the matter disclosed in the specification of a patent extends beyond that disclosed in the application. Similarly,  a patent may be revoked under s.72 (1) (c) if the specification does not disclose the invention clearly enough and completely enough for it to be performed by a person skilled in the art. The claimant,  Playhut Inc. ("Playhut"), sued Spring Form Inc. ("Spring Form") for  revocation of a patent on both of those grounds and Spring Form counterclaimed for infringement of its patent.

The Issues

The patent in suit was a lightweight, self-erecting, collapsible tent made up of a number of side components each of which consisted of a frame of flexible material capable of coiling up on itself covered by a layer of fabric under tension.  Playhut manufactured and distributed a collapsible play tent that Spring Form believed to infringe its patent.  Playhut replied  that its product would not have infringed the patent had it been granted in the terms of the the application and any  difference between the application and the patent as granted was the result of added matter. Alternatively, it argued that the specification did not disclose the invention clearly and completely enough for it to be performed by a person skilled in the art.

Added Matter

The only  differences between the specification of the patent and that of the application lay in the scope of the claims. The first difference was that claim 1 of the application provided for hinging of the side panels between the top right of each component and the top left of its neighbour whereas there was no such restriction on the location
of the hinges in claim 1 of the patent. The second was that claim 1 of the application referred to a "third means" for hinging the side members together and a "fourth means" for holding the tent in its expanded, upright configuration, suggesting that the holding mechanism must be something other than the hinge. Because claim 1 of the patent (unlike the corresponding claim of the application) made no distinction between hinging and holding, claim 1 of the patent caught Playhut's tent. Playhut's hinge allowed its side components to rotate in relation to each other and also stopped the feet of its structure from splaying out. Playhut argued that if something falls within the scope of a claim it is impliedly disclosed by that claim. If the claim of a patent catches something that would not have been caught by the corresponding claim in the application, it must follow that the matter disclosed in the patent extends beyond that disclosed in the application.

Judgment

Laddie J rejected that contention on the ground that there was nothing in the Act to prevent an inventor from widening the scope of his or her claims before grant. The only prohibition to the extension of patent protection lies in s. 76 (3) (b) which applies where a patent has been granted. If Playhut were correct the restriction in s. 69 (2) (b) confining the scope of proceedings that a patentee may bring in respect of infringements before grant to acts to those that would have infringed the application
would be otiose. Furthermore, s. 15 (1) of the Act allows an application to be made without any claims at all.

The judge explained that these were "not simply arid points of statutory construction":

"The provisions I have referred to are designed to make the patent system work. Because of the importance of securing an early priority date, any inventor is obliged to file his application for a patent as soon as possible. At that time he will normally not have had a chance to work out in detail the scope of the inventive concept he thinks he has discovered. He may have had little time to discuss his invention with professional advisers. Although his application can include claims, it would be harsh and subversive of the system if he were then to be tied to their precise scope thereafter."

He added that there were safeguards to the abuse of that system:

"These considerations do not mean that an inventor is given a free hand to widen out his claims at will. It may well be that if he goes too far he will take his claimed monopoly beyond the concept he has invented. If so, insufficiency may result. Further he may try to secure better protection by writing into his claims features or combinations of features which are not disclosed expressly or
implicitly in the application as filed. That may constitute adding matter."

However, he concluded that it was not sufficient to say, as Playhut did, that mere changes in scope of claim amounted to "added matter".

Test for "Added Matter"

In determining whether there had been "added matter", Laddie J referred to Aldous J's judgments in Bonzel v Intervention (No. 3) [1991] RPC 553 and AC Edwards Ltd. v Acme Signs and Displays Ltd. [1990] RPC 621. In Bonzel the judge said, at page 574, that the decision as to whether there was extension of disclosure must be made on a comparison of the two documents read through the eyes of a skilled addressee. The task of the court is to:

	ascertain through the eyes of the skilled addressee what is disclosed, both explicitly and implicitly in the application;
	do the same in respect of the patent as granted; and
	compare the two disclosures and decide whether any subject matter relevant to the invention has been added whether by deletion or addition.

The comparison is strict in the sense that subject matter will be added unless such matter is clearly and unambiguously disclosed in the application either explicitly or implicitly. But the strictness of that rule is qualified by Aldous J's observation in Edwards that not everything within a claim is disclosed though it may fall within the ambit of the claim.

Applying those principles, Laddie J could find nothing that had been added to the specification. Claim 1 of the patent specification did not disclose hinges located elsewhere than the top left and right hand corners of each side component but, if it did, then so did one of the drawings of the patent application. Moreover, the specification did not indicate that the precise location of the hinges was critical. Moreover, there was nothing in the application that required the hinging and holding mechanisms to be separate and distinct but, if it did, the  drawings already mentioned also showed them to be combined.

Insufficiency

The complaint was not that a skilled addressee would experience difficulty in making tent-like structures across the breadth of the claims but that the claims exceeded the inventor's disclosure as in Biogen Inc.v Medeva Plc [1997] RPC 1. Playhut argued that Spring Form had disclosed a tent where the hinges lay at the top left and right hand corners of each side member but claimed something more. That was essentially the same as the "added matter" point which his lordship rejected for the same reasons.

Infringement

The only substantial defence to infringement was a "squeeze", namely that the claim alleged to have been infringed required the hinging and holding mechanisms to be separate and distinct, or that the claim was bad for added matter. Since both of those arguments had failed, it followed that the patent was valid and had been infringed.

Comment

The point of interest in this case is Laddie J's observation that adding features or combinations of features that are not disclosed expressly or impliedly in the application in order to procure better patent protection may constitute "added matter" for the purposes of s. 72 (1) (d). Although he rejected Playhut's construction of the section and threw out its case on the facts, he appears to have accepted much of its underlying argument. The practical difficulty that arises from that observation is determining when features or combinations of features are not disclosed impliedly having regard to Aldous J's dicta in Edwards (on which the judge relied) that not everything is disclosed in a claim. Laddie J's remarks together with Aldous J's obiter dicta are likely to haunt skeleton arguments on added matter for years to come.

 

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