Sudarshan Chemical Industries Ltd v Clariant Produkte (Deutschland) GmbH

A patent infringement claim fails where the alleged product is no more than the inevitable result of carrying out the prior art, including ordinary and obvious process optimisation. Such a product claim lacks novelty and inventive step. A use claim also lacks inventive step where the proposed use is an obvious application of the prior-art product.

An amendment adds matter unless the amended subject matter is clearly and unambiguously disclosed, expressly or implicitly, in the application as filed. The test is not obviousness, and intermediate generalisation is impermissible where features disclosed only in a particular context are removed from that context. A disclaimer cannot cure an anticipation which is relevant, rather than accidental, or cure lack of inventive step.

The claimant manufactured Pigment Yellow 191 and sought revocation of the defendant’s patent concerning the beta polymorph of that pigment. It also sought declarations of non-infringement and relief for unjustified threats. The defendant counterclaimed for infringement.

The claimant relied principally on a Gillette Safety Razor Co v Anglo-American Trading Co defence, contending that its products were made by the prior-art process, with only ordinary commercial variations. It also challenged the patent’s validity, opposed conditional amendments, and alleged actionable threats to its customers.

The issues included whether the processes worked the prior art, whether the patent claims were novel and inventive, whether proposed amendments added matter, and whether the statutory defence to threats was established.

1. Gillette defence and validity. The claimant’s Old and New Processes were ordinary and obvious commercial implementations of Example 1 of the prior-art patent. The evidence established that the wet cake produced by Example 1 contained 100% beta polymorph, and that ordinary process variations also produced that result. The Gillette defence therefore succeeded in relation to the product claims.

2. The product claims were invalid for lack of novelty and inventive step. The use claims were invalid for lack of inventive step because using pigment wet cake in the specified applications, including polymers, was obvious to the skilled addressee.

3. Amendments. The proposed amendments remained anticipated or obvious. Applying Bonzel (T.) v Intervention Ltd (No 3), as further explained and approved in European Central Bank v Document Security Systems, the original application and amended specification had to be construed through the eyes of the skilled addressee and compared strictly. Subject matter was added unless clearly and unambiguously disclosed, expressly or implicitly. This was not an obviousness test. The proposed claim concerning dry grinding and particular uses introduced an impermissible intermediate generalisation and added subject matter contrary to section 76 of the Patents Act 1977.

4. The alternative disclaimer was also impermissible. The prior-art disclosure was not accidental because it came from the original PY 191 patent and was directly relevant to the invention. A disclaimer could not be used to overcome lack of inventive step. The approach in LG Philips LCD Co Ltd v Tatung (UK) Ltd was applied.

5. Threats. The letter objectively threatened patent proceedings in relation to customers as well as the claimant. Applying Luna Advertising Co Ltd v Burnham & Co and John Summers v Cold Metal Process, a threat may consist of an expression of threatened proceedings in relation to a person, even if it is not communicated directly to that person.

6. The defendant failed to establish the defence under section 70(2A) of the Patents Act 1977. Although its witness did not know and had no reason to suspect invalidity, the defendant had taken no adequate steps to investigate. Its knowledge that prior-art material contained the beta polymorph gave it reason to suspect that the patent was invalid.

7. The patent was revoked and the threats claim succeeded.