Thursday, December 30, 2010

An Old Pharma Decision: Bombay high Court (1968) - II

In the last post, we stopped at the introduction to the issue of claim construction for infringement; to reiterate, the Bombay High Court stated that in determining infringement, a Court needs to construe the claims of the patent and claims alone, unless ambiguity in the language of the claims forces the Court to refer to the body of the specification. 

Claim Construction for Infringement

Keeping with the above view, the Court undertook construction of Claims 1, 11 and 22 of the plaintiff’s patent. The claims were as follows:

1. A process for the manufacture of sulphonylureas of the general formula R-SO. 2-NH-CO-NH-R. 1, in which R represents a phenyl radical which may contain one or two substitutes selected from alkyl and alkoxy residues, the alkyl group of which containing at most 8 Carbon atoms, and halogen atoms, or represents an alipahtic or cycloaliphatic Hydro-Carbon radical containing 3 to 8 Carbon radicals (as Dr. Aumuller has pointed out, the word "radicals" here is a mistake and should be "atoms") and R. 1 represents an aliphatic or cycloaliphatic Hydra-Carbon radical containing 2 to 8 Carbon atoms, and of the salts thereof, wherein compounds of the formula R - SO. 2.-X and Y-R.1 are reacted together in which X and Y are groups which on reaction together form a urea linkage as defined above or a linkage readily convertible thereto. 

11. A process as claimed in claim 1 wherein thioureas of the formula R-SO. 2-NH-CS-NH-R. 1 are treated with agents eliminating the sulphur, R and R. 1 having the meanings given above.

22. The compounds of the formula shown in Fig. 6 of the drawings, whenever obtained according to claims 1-15. 

If one were to construe Claim 1, it may be broken down thus:

A. The Claim is directed at a process for manufacture of sulphonylureas
B. The sulphonylureas so manufactured must be of the general formula R-SO. 2-NH-CO-NH-R. 1
C. The Claim further goes on to identify R and R1 as belonging to a particular group of compounds with limitation on the maximum number of carbon items that R and R1 each may have
D. The characterising portion of the Claim, which begins with “wherein”, states that the urea linkage defined in the introduction of the Claim is obtained by reacting R - SO. 2.-X and Y-R.1 together, or by directly converting the linkage so obtained from the reaction of the two constituents.

In other words, the product of the reaction between R - SO. 2.-X and Y-R.1 shall be suphonylurea of the general formula R-SO. 2-NH-CO-NH-R. 1 , or a thiourea which can be further directly  converted to a suphonylurea of the said general formula.

If this is accepted, it is clear that Claim 11 fell squarely under the second situation envisaged in Claim 1 since it spoke of desulphurisation of a thiourea of the formula R-SO. 2-NH-CS-NH-R. 1, using agents to eliminate sulphur. 

It is pertinent to point out here that neither Claim 1 nor Claim 11 restricted themselves to a specific thiourea, or a particular method of desulphurisation of thioureas or the agents used for desulphurisation. Consequently:
a.  so long as the thiourea, used as the base material for production of sulphonylurea, restricted itself to the general formula claimed in Claim 11,
b. with the groups R and R1 being delimited by the limitations set forth in Claim 1,
c. all such thioureas which could be desulphurised to yield, directly or indirectly, a sulphonyl urea of the formula mentioned in Claim 1, fell within the scope of the Plaintiffs’ patent.

The Court too took an identical view on construction of the claims. The Court further noted that there could be several compounds that could be manufactured using the process claimed in Claim 1; consequently, Tolbutamide was but one of the compounds which could be manufactured using the Plaintiffs’ patented process. 

It was admitted by the defendants in their written statement that they manufactured Tolbutamide by desulphurising substituted benzenesulphonyl-thioureas with hydrogen peroxide. The Court took the view, that although this process of the defendants may have been based on the licensed process claimed in IN 64323 of the Haffkine’s Institute, the process employed by the defendants must be deemed to have infringed the plaintiff’s patent in light of the Court’s construction of the plaintiffs’ claims. This was so, because nowhere did the plaintiff’s patent exclude use of hydrogen peroxide as a desulphurising agent.

Grounds of Invalidity of the Plaintiffs' Patent

The Court then proceeded to deal with the defence of invalidity of the patent raised by the defendants. The grounds raised to allege invalidity were:
(1) Insufficiency of description
 (2) Want of novelty
 (3) Lack of inventive step and
(4) Want of utility

A. Insufficiency of Description

Citing Halsbury, the Court observed thus:

“..the claim need only be as clear as the subject admits, and that a patentee need not so simplify his claim as to make it easy for infringers to evade it.”

Further, according to Halsbury:

“..the patentee's duty is not to prevent all possible argument as to whether there is or is not infringement in particular cases, but to enable the court to formulate the questions of fact to be answered”

Let’s try and understand the import of the above proposition because I am not really clear as to context of the application of the above proposition. Probably, (and I could be wrong here), what is sought to be conveyed is that, in a case of infringement, the patentee is not expected to provide answers to all possible counter-arguments, including those which have not been raised by the defendant in a particular suit

In other words, his only duty is to assist the Court in formulating questions of fact with respect to the dispute on hand, and not every possible issue which does not figure in the dispute on hand and which may be raised in future disputes. This, in my opinion, is relevant from a litigation point of view, because it requires the Court to cast only such duty upon the plaintiff/patentee as is necessary for resolution of issues in the suit, and not beyond.

On what a complete specification must contain to successfully survive the allegation of insufficiency, Halsbury says:
(1) the complete specification must describe "an embodiment" of the invention claimed in each of the claims and that the description must be sufficient to enable those in the industry concerned to carry it into effect "without their making further inventions"; and
(2) that the description must be fair i.e. it must not be unnecessarily difficult to follow.

In the instant case, the Court took the view that, since Claim 11 read with Claim 1 made it abundantly clear that all known methods of desulphurisation of thioureas would fall within the ambit of the claims, no further support from the specification was needed because there was no room for ambiguity.

Further, the claims must be understood, not so much as claiming a method of desulphurisation of thioureas, but primarily as claiming the method of synthesis of such sulphonylureas which have anti-diabetic properties. In other words, the crux of the patent lay in selecting such base material which upon further reaction generated the desired sulphonylurea, hence the limitation on the identity of the groups X, Y, R and R1 in the formula. (This throws up an interesting question, which will be taken up in another post)

Also, critically, the Court noted that it was not necessary for the patentee to describe processes which were common knowledge to the target audience of the patent- a highly-skilled group of practitioners of the relevant art. (This is another point of research...)

Finally, since as many as 40 examples had been provided in the specification to support Claim 1, the allegation of insufficiency of description, in the Court’s view, held no water.

The remaining grounds of invalidity shall be discussed in the next post.

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