Celltech Chiroscience Ltd. v Medimmune Inc.

Celltech Chiroscience Ltd. v Medimmune Inc.

The majority held that the amendment to the patent claim made donor residue at position 23 compulsory, thereby surrendering the right to assert infringement by equivalents at that position. The territory surrendered by the amendment included all amino acids at position 23 other than the donor residue, and Celltech was estopped from asserting equivalence for that position. The presumption of estoppel was not rebutted, and the rationale for the amendment was not tangential to the equivalent in question.

Parties
Appellant: Celltech Chiroscience Ltd; Respondent: MedImmune Inc.
Jurisdiction
England and Wales
Judgment Date
17 July 2003
Procedural Posture
Civil Appeal (patents) / Court of Appeal Judgment on Appeal and Cross Appeal From Patents Court
Outcome
Appeal dismissed; cross-appeal allowed; action dismissed
Legal Topics
Doctrine of Equivalents, Prosecution History Estoppel, Patent Infringement, Amendment Estoppel, Argument Estoppel
Intellectual Property Law Patent Law Doctrine of Equivalents Prosecution History Estoppel Patent Infringement Amendment Estoppel Argument Estoppel

Case Brief

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Parties

Celltech Chiroscience Ltd

Appellant

MedImmune Inc.

Respondent

Procedural Posture

Civil Appeal (patents) / Court of Appeal Judgment on Appeal and Cross Appeal From Patents Court

Legal Issues

  1. 1 Whether Celltech is precluded from relying on the US doctrine of equivalents by virtue of prosecution history estoppel (Amendment and Argument Estoppel)
  2. 2 Whether the amendment to the patent claim surrenders the right to assert infringement by equivalents at position 23
  3. 3 Whether there was an unmistakable assertion precluding reliance on equivalents

Ratio Decidendi

The majority held that the amendment to the patent claim made donor residue at position 23 compulsory, thereby surrendering the right to assert infringement by equivalents at that position. The territory surrendered by the amendment included all amino acids at position 23 other than the donor residue, and Celltech was estopped from asserting equivalence for that position. The presumption of estoppel was not rebutted, and the rationale for the amendment was not tangential to the equivalent in question.

Court Disposition

Appeal dismissed; cross-appeal allowed; action dismissed

Orders

  • Order of Jacob J dismissing the action stands
  • Costs awarded to MedImmune, £60,000 to be paid on interim basis