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On January 27, 2012, the Japanese Intellectual Property High Court (JIPHC) issued an en banc decision on the claim construction of a product-by-process claim, i.e., whether the technical scope of the product-by-process claim should be limited to the product produced by the claimed process.

This is a patent infringement case H22(Ne)10043 and the Japanese Patent at issue (No. 3,737,801) has a product-by-process claim relating to pravastatin sodium, which reads as follows:

1.  Pure pravastatin sodium containing less than 0.5% pravastatin lactone and less than 0.2% epiprava, prepared by a process comprising the steps of:

a) forming an organic solution of pravastatin; 
b) precipitating the pravastatin as an ammonium salt; 
c) purifying the pravastatin salt by recrystallization; 
d) transposing the ammonium salt to pravastatin sodium; and,
e) isolating the pravastatin sodium.

The issue in this case was whether technical scope of the product-by-process claim should be limited to the product produced by the process.  In addressing this issue, the court categorized product-by-process claims into two groups – one group in which the product was claimed in the form of a product-by-process claim due to the fact that there existed any circumstances that it was impossible or difficult at the time of filing the application to directly identify the product by its structure or property (referred to as “genuine product-by-process claim”), and the other group in which the product was claimed in the form of a product-by-process claim despite the fact that there was not any circumstance that it was impossible or difficult at the time of filing the application to directly identify the product by its structure or property (referred to as “ingenuine product-by-process claim”).

Then, the JIPHC defined the technical scopes of the genuine and ingenuine product-by-process claims as follows:
(i)  if the product-by-process claim is the genuine product-by-process claim, the technical scope of the invention should not be limited to the product produced by the process defined in the claim and the accused product should be construed to be the same as the product produced by the claimed method
, and
(ii) if the product-by-process claim is the ingenuine product-by-process claim, the technical scope of the invention should be limited to the product produced by the claimed method.
The court also stated that, where a manufacturing process is described in a product claim, a party who argues that the claim is a genuine product-by-process claim should bear a burden of proof that it was impossible or difficult at the time of filing the application to directly identify the product by its structure or property and, if the party failed to demonstrate that, the claim should be treated as an ingenuine product-by-process claim and its technical scope be construed literally as it is defined in the claim.