On 23 May 2007, the High Court finally found for Lockwood in Lockwood Security Products Pty Ltd v Doric Products Pty Ltd (No 2)  HCA 21. It restrained Doric from infringing certain claims of Lockwood's Australian patent no. 702534.
The patent is also the subject of an important decision handed down by the High Court in connection with the requirement of fair basis (Lockwood Security Products Pty Ltd v Doric Products Pty Ltd  HCA 58).
In that case, the High Court remitted matters concerning inventive step back to the Full Federal Court to decide infringement, insufficiency and obviousness.
This case relates to the appeal to the High Court by Lockwood. The Full Court found that independent claim 1 and a further important claim, claim 13, both lacked inventive step.
It's useful to recite claim 1 here, broken up into integers:
A latch assembly including,
(i) a casing,
(ii) a latch bolt mounted on the casing so as to be movable relative thereto between an extended latching position and a retracted release position,
(iii) a first actuator operable from an inner side of the assembly to cause movement of the latch bolt to said release position,
(iv) locking means operable from said inner side of the assembly to adopt an active condition and thereby render said first actuator inoperable,
(v) a second actuator operable from an outer side of the assembly to cause movement of the latch bolt to the release position, and
(vi) lock release means which is responsive to said operation of the second actuator so as to thereby render said locking means inactive.
Integers (i) to (v) were the integers of a patent, also owned by Lockwood and the closest prior art presented.
It was Doric's contention always that the invention defined by the above claim was obvious in the light of the previous Lockwood patent. Doric held that integer (vi) did not result in an invention that involved an inventive step.
Some background will help. The previous Lockwood patent covered an improvement to a latch assembly that could easily be unlocked from the inside. It was the type that locks automatically when the door closes.
The problem that led to the previous Lockwood patent was that criminals could get out through the door with large, expensive items. Thus, with the previous patent, once the door locked, it required a key to get out from the inside. That can be seen in integers (i) to (v).
But if the door was locked and there was an emergency, you would need to find the key to get out in a hurry.
So Lockwood came up with integer (vi). The latch bolt was released if the door had been opened with the key from the outside. You could then open the door from the inside without the key.
The Main Issues
The Full Federal Court had raised the concept of an "implicit corollary submission". In the background section of the Lockwood patent: "...key operation of the latch from the outside of the door will not release the lock. That can lead to serious problems in circumstances where the door needs to be opened urgently from the inside."
The Full Court reasoned that the specification admitted that it was common general knowledge that the outside key did not release the lock. The Full Court accepted Doric's contention that the
specification contained the "implicit corollary admission" that a solution to the deficiency of the prior art was common general knowledge.
A claim must not define an invention which is obvious to a person skilled in the art. The test is made at the priority date. Reference is made to the common general knowledge at the priority date. You can consider material that the skilled person would have "ascertained and
understood" as being relevant.
Admissions made in a specification are consistent with conventional drafting practice. They highlight the invention in light of the prior art. They facilitate an understanding of the relevant inventive step. The Court must weigh admissions with evidence from skilled persons.
You can consider an admission that some integers are common general knowledge. You can consider it with witnesses' evidence whether others are also common general knowledge. But they will not necessarily be conclusive. The trial judge must weigh all the evidence. It is a contradiction in terms to say a solution is obvious if the problem is well-known but no-one has mentioned the solution.
The nominal skilled person is key to inventive step. Would adding an integer be regarded as technically possible and practical to him? A court cannot substitute its own deduction or proposition.
In short, use of an "implicit corollary admission" is erroneous. It ignores the rule that the claim has to be interpreted in the shoes of the skilled person in light of the common general knowledge.
As it turned out, claim 1 was found to define an invention that was not new. A storeroom lock assembly was found that could be described by the integers of claim 1.
Note the distinction between novelty and inventive step. Claim 1 could lack novelty. But it could still incorporate an inventive step.
However, Lockwood was happy to let claim 1 go. It was accepted that Doric had been infringing a lock assembly covered by claim 13. Claim 13 was dependent on claim 1 and was more specific. It described a rim mounted lock. It had a detent mechanism that moved radially.
The storeroom latch assembly had a detent mechanism that moved axially. As a result, the storeroom latch assembly was in a different category of lock to that described by claim 13.
For Lockwood and Doric, the critical issue was whether claim 13 defined an inventive step or not.
Doric tried to argue that the storeroom lock should be considered for inventive step. It held that it was relevant for claim 1 and therefore should be relevant for claim 13. Doric relied on its incorrect submission that claim 1 was invalid for lack of inventive step.
But each claim must be considered on its own merits. What is relevant for claim 13 must be considered with reference to claim 13. A dependent claim is to be regarded as defining an invention in its own right. Dependency is just a tool for reducing excessive verbiage.
A person skilled in the art would not consider the storeroom lock as being relevant. Because the skilled person would not apply an axially operating detent mechanism to a problem with a rim mounted lock.
Also, none of the witnesses mentioned using the storeroom lock.
Claim 13 was therefore valid and enforceable. The storeroom lock was the only prior art found that addressed a similar problem. However, it did not qualify as either common general knowledge or information that would be relevant to the skilled person.
You will immediately note the divergence with US practice. Admissions induce paranoia in US practitioners. It's a relief to me that we have taken a common-sense approach.
It's a basic and often misunderstood rule. Read the claims through the eyes of the nominal skilled person. Subjectivity has no place in testing claims for lack of inventive step. It raises the issue of whether or not patent examiners should actually be permitted to examine for inventive step. But that's for another post.