Patent Scope

Claims as the Boundary

• The claims are the legal definition of the inventor's exclusive right
• The patent specification and drawings provide context, but the claims define the metes and bounds
• 35 U.S.C. § 112(b): claims must 'particularly point out and distinctly claim the subject matter which the inventor or a joint inventor regards as the invention'

Claim Construction

• The process of determining what each claim term means
• This is a question of LAW decided by the judge (Markman v. Westview Instruments, S.Ct. 1996)
• Different claim constructions can dramatically change the scope of protection
• PHILLIPS v. AWH (Fed. Cir. 2005 en banc): the controlling case for claim construction
• The hierarchy of evidence: INTRINSIC EVIDENCE (primary): (1) the claims themselves (context of other claims, same term should mean the same thing in different claims)
• (2) the specification (most important context; defines the invention; may define terms)
• (3) the prosecution history (record of examination; statements made by the applicant)
• EXTRINSIC EVIDENCE (secondary): technical dictionaries
• Expert testimony
• Textbooks
• Can help understand the technical field but cannot override clear intrinsic evidence

Ordinary Meaning

• Claim terms are generally given their ordinary meaning as understood by a POSITA at the time of invention
• If the specification provides a special definition, the specification's definition controls (even if different from the ordinary meaning)

Specification as Lexicographer

• An applicant can act as his/her own lexicographer — if the specification clearly defines a term with a specific meaning, that definition controls
• This is both a tool (can expand ordinary meaning) and a trap (inadvertent limiting definitions in the spec).

Prosecution History Disclaimer

• When an applicant makes a clear and unmistakable statement during prosecution that limits claim scope to overcome a rejection, that statement creates a 'disclaimer'
• The claim is interpreted as excluding the disclaimed subject matter
• Omega Engineering v. Raytek Corp. (Fed. Cir. 2003): clear and unmistakable disclaimer requires more than the applicant's silence — must be an explicit statement or argument that clearly surrenders scope

Prosecution History Estoppel

• Specifically applies to doctrine of equivalents claims
• If a narrowing amendment was made for reasons related to patentability, the patentee is estopped from using DOE to recapture the surrendered scope (Festo, S.Ct. 2002)

Narrowing Amendments

• Adding a limitation to a claim to overcome a rejection narrows the claim's scope
• The claim no longer covers what was removed

Examiner Interviews

• Statements made during examiner interviews may create disclaimer
• Less formally documented but can be used

Avoiding Disclaimer in Prosecution

• Use careful, precise language in arguments
• Do not make unnecessarily broad disclaimers to overcome a rejection
• The disclaimer should track the rejection narrowly
• If a narrowing amendment is required, note that the amendment is for reasons other than patentability (e.g., to clarify, not to overcome prior art) — though this claim is subject to scrutiny

Navigating Competing Evidence

• Sometimes the specification suggests a broad scope while the prosecution history suggests a narrow scope
• Courts look for a 'clear and unmistakable' disclaimer before applying a narrowing prosecution history interpretation.

The Doctrine

• The claim differentiation doctrine provides that different claims in a patent should presumptively have different scopes
• If one claim is broader than another, the broader claim should be interpreted broadly enough to differ from the narrower claim

Legal Basis

• 'it is a well established rule of claim construction that the scope of a patent claim is not to be limited by the language of a dependent claim' (Autogiro v. United States, Ct. Cl. 1971)
• STRONG vs.

When Claim Differentiation is Rebutted

• The presumption is rebutted by strong contrary evidence: explicit definitions in the specification
• Clear prosecution history disclaimer
• The doctrine applies only as a 'guide' — not an absolute rule

Strategic Use

• Patent drafters use claim differentiation to argue that independent claims are broader than they might otherwise appear
• Independent claim 1 + dependent claim 2 (adding 'wherein X') + dependent claim 3 (adding 'wherein Y') → independent claim 1 should be read as covering cases without X and without Y

Claim Differentiation Between Independent Claims

• Different independent claims using different language should each be given different scope
• Redundant claims (same effective scope as another claim) are discouraged though not prohibited.

Meaning

• The claim covers the listed elements AND allows for additional elements
• A product with the claimed elements PLUS more elements still infringes

Most Protective

• 'comprising' claims are the broadest and most commonly used
• Preferred in application drafting when broader scope is desired
• 'CONSISTING OF' (CLOSED CLAIM): 'consisting of' means the claim is LIMITED to the listed elements
• A product with any additional element does NOT infringe

Example

• 'a composition consisting of compound A and compound B' covers ONLY compositions with exactly A and B
• Adding compound C would not infringe

Use Case

• Used when the listed elements are critical and adding other elements would be problematic
• Less common in utility patents but common in pharmaceutical composition claims where a specific formulation is claimed
• 'CONSISTING ESSENTIALLY OF': a middle ground between 'comprising' and 'consisting of'
• The claim covers the listed elements plus elements that do not MATERIALLY AFFECT the basic and novel characteristics of the claimed invention

Used in

• Pharmaceutical and biotech claims to cover formulations with minor additives that don't change the core properties
• Requires definition of what 'basic and novel characteristics' are

Preamble

• The claim preamble (the introductory phrase before 'comprising') may or may not limit claim scope
• A preamble that gives 'life and meaning' to the claim elements limits scope
• A preamble that merely states the intended use does not limit scope
• Contested in many cases.

Applicant Strategies to Broaden Scope

• Use 'comprising' language
• Minimize limiting language in independent claims
• Use broad functional claim language for method steps
• Challenge examiner's proposed narrowing constructions in office action responses
• Avoid making arguments that unnecessarily narrow claim scope

Examiner Reactions

• Examiners sometimes apply a broader construction to find prior art
• USPTO applies BRI (broadest reasonable interpretation) during prosecution
• BRI is different from the Phillips standard applied in court (BRI is explicitly broader)

Transitions from BRI to Phillips

• When a patent issues, courts apply Phillips (not BRI)
• This means claims may be construed narrower in court than during prosecution
• Patent owners sometimes find that their broad prosecution claims are interpreted more narrowly by courts

In Litigation — Markman Hearings

• A Markman hearing is a formal claim construction hearing before the judge
• Parties submit claim construction briefs
• Experts testify about technical meaning and context
• The court issues a claim construction order
• The parties then apply the construed claims to the accused product/method

Impact of Claim Construction

• A broader construction helps the patent owner (infringement is easier to establish)
• A narrower construction helps the accused infringer (infringement is harder to establish)

Inter Partes Review and PTAB

• IPR uses the same Phillips standard as district court (post-SAS Institute change)
• Before 2018, PTAB used BRI in IPR

In Appeals

• Federal Circuit reviews claim construction DE NOVO (fresh look; no deference to lower court)
• Underlying factual findings get deferential review (clear error)
• Split standard from Teva Pharmaceuticals (S.Ct. 2015).