Purposive Construction of Compound Claims

Date Published

It would be uncommon for examiners to have sufficient evidence to take a purposive construction of compound claims.

An example of the use of purposive construction related to the compound rapamycin. The term "rapamycin" was construed as including derivatives. The judge asked three questions:

  • does the variant have a material effect on the way that the invention works;
  • would it have been obvious that the variant would not have a material effect on the way the invention works; and
  • would a reader have understood from the claim that strict compliance with the primary meaning was an essential requirement of the invention.

See American Home Products Corp v Novartis Pharmaceuticals UK Ltd [2001] RPC 8.