Invalidity Contentions in Patent Litigation: Strategies, Prior Art, and Best Practices

2. Understanding Patent Invalidity

2.1 What is Patent Invalidity?

Patent invalidity refers to the legal argument that a granted patent should not have been issued because it fails to meet the requirements set by 35 U.S.C. §§ 101, 102, 103, or 112. If a court finds a patent invalid, the patent cannot be enforced, rendering any infringement claims moot.

2.1 Key Grounds for Patent Invalidity

1. Anticipation (§102) – Single Prior Art Reference

   • A patent is invalid if a single prior art reference (published before the patent’s priority date) discloses all elements of a claimed invention.
   • The prior art must be publicly available (patents, scientific articles, products).

2. Obviousness (§103) – Combination of References

   • A patent claim is invalid if two or more prior art references, when combined, make the invention obvious to a person having ordinary skill in the art (PHOSITA).
   • Courts apply the Graham v. John Deere Co. test to determine obviousness:
     1. Scope and content of prior art.
     2. Differences between the prior art and the patent claim.
     3. Level of skill in the relevant field.
     4. Any secondary considerations (commercial success, industry recognition).

3. Lack of Enablement (§112, ¶1) – Not Sufficiently Detailed

   • A patent must teach how to make and use the invention without undue experimentation.
   • If a patent claim covers a broad concept but fails to provide enough technical details, it can be invalidated.

4. Indefiniteness (§112, ¶2) – Ambiguous Claims

   • Patent claims must be clear and definite. If they are too vague or open to multiple interpretations, they can be invalidated under Nautilus, Inc. v. Biosig Instruments, Inc.

5. Lack of Written Description (§112, ¶1) – Not Fully Disclosed

   • A patent must fully describe the claimed invention in the original filing.
   • If the patent owner tries to claim something broader than what was originally disclosed, it can be invalidated.

6. Patentable Subject Matter (§101) – Abstract Ideas, Laws of Nature

   • Software patents, business methods, and diagnostic tests often face invalidity challenges under Alice Corp. v. CLS Bank International.
   • If a patent is merely an abstract idea or a law of nature without an inventive concept, it is ineligible for patent protection.

2.2 Burden of Proof in Patent Invalidity

• Patents are presumed valid under 35 U.S.C. § 282.
• The challenger (defendant) must prove invalidity by clear and convincing evidence (higher than preponderance but lower than beyond reasonable doubt).
• USPTO vs. Court Invalidity Standards:
  • USPTO (Inter Partes Review, Post-Grant Review): Preponderance of evidence standard.
  • Federal Court: Clear and convincing evidence standard.

2.3 How Invalidity Impacts Litigation

• If any claim in a patent is invalid, it cannot be enforced.
• Invalidity defenses are often presented alongside non-infringement arguments to strengthen a litigation position.