Claim Interpretation

Philips v. AWH Corp. (Fed. Cir. 2005 en banc) is the controlling authority for patent claim construction in both district courts and at the PTAB: THE PHILIPS STANDARD: claim terms receive the 'ordinary and customary meaning' that a person of ordinary skill in the art (POSITA) would have given to the term at the effective filing date of the patent application; claims are NOT read in isolation — they are interpreted in the context of the intrinsic record: (1) the claim language itself; (2) the specification; (3) the prosecution history; INTRINSIC RECORD — THE HIERARCHY: (1) CLAIM LANGUAGE: the starting point for claim construction; words in a claim have their ordinary meaning unless the patentee has departed from that meaning; claims also serve as guides to the scope of other claims (claim differentiation); (2) SPECIFICATION: the specification is 'the single best guide to the meaning of a disputed term' (Philips); the specification provides context for how terms are used; the specification can redefine a term (lexicography) or can narrow a term through disavowal; BUT: courts should not import limitations from the specification into the claims — the claims define the invention; (3) PROSECUTION HISTORY: the prosecution history can limit claim scope through: (a) narrowing amendments (prosecution history estoppel — Festo); (b) arguments distinguishing prior art (prosecution disclaimer); EXTRINSIC EVIDENCE: evidence outside the intrinsic record; includes: expert testimony (declarations, deposition); inventor testimony; technical treatises; dictionaries; Philips held that extrinsic evidence is LESS RELIABLE and should only be used when intrinsic evidence is genuinely ambiguous; extrinsic evidence cannot contradict clear intrinsic evidence; WHY PHILIPS MATTERS FOR BOTH PROSECUTION AND LITIGATION: claim construction determines INFRINGEMENT scope and INVALIDITY scope; broad construction = more likely to find infringement (good for patentee) but also more prior art vulnerability (bad for patentee); narrow construction = less likely to find infringement (bad for patentee) but stronger against prior art; PTAB ADOPTED PHILIPS IN 2019: prior to 2019, PTAB applied the Broadest Reasonable Interpretation (BRI) standard in IPR proceedings; the USPTO changed its rules in 2019 to adopt the Philips standard in all AIA proceedings (IPR, PGR); this aligns PTAB claim construction with district court construction.

Lexicography and disavowal are the two main mechanisms by which a patent drafter can affect the ordinary meaning of claim terms: LEXICOGRAPHY — INTENTIONAL REDEFINITION: the patent drafter can act as his or her own lexicographer and EXPLICITLY DEFINE a claim term in the specification; when the drafter defines a term, that definition controls over the ordinary meaning; REQUIREMENTS FOR A VALID LEXICOGRAPHY: (1) the specification must provide a clear and unmistakable definition; phrases like 'X means Y' or 'as used herein, X refers to...' create explicit definitions; (2) the definition must be consistent with the claim language; (3) the definition applies throughout the patent and prosecution history; EXAMPLES OF LEXICOGRAPHY: 'Widget' as used in this specification means a mechanical fastener with at least three threads; 'substantially' as used herein means within 10%; STRATEGIC USE: defining terms in the specification can EXPAND ordinary meaning (to capture more competitors) or NARROW it (to avoid prior art); DISAVOWAL — NARROWING THROUGH CLAIM LANGUAGE OR SPECIFICATION: disavowal (also called 'prosecution disclaimer') occurs when the patentee explicitly disavows (gives up) certain subject matter through: (1) CLAIM LANGUAGE: express limitations in the claims themselves; (2) SPECIFICATION STATEMENTS: when the specification explicitly characterizes certain subject matter as outside the invention; example: 'The present invention does NOT include aqueous formulations'; this statement disavows aqueous formulations even if the claim language might literally cover them; (3) PROSECUTION HISTORY: when the applicant argued during prosecution that the invention is distinguished from prior art because it lacks a certain feature; this argument creates a prosecution disclaimer limiting the claim's scope; REQUIREMENTS FOR DISAVOWAL: must be clear and unambiguous — an equivocal statement is not a disavowal; a single statement in passing is not enough; CLAIM DIFFERENTIATION vs. DISAVOWAL: claim differentiation creates a PRESUMPTION that different claims have different scope; disavowal is a CONCLUSIVE limitation; if there is a conflict between claim differentiation and disavowal, the disavowal typically wins because it was an explicit act by the patentee.

Claim differentiation is a presumption that different patent claims in the same patent have different scope: THE DOCTRINE: courts presume that if two claims are different, they have DIFFERENT SCOPE; if one claim has a limitation that another does not, the claim WITHOUT the limitation is presumed to have a BROADER scope that does NOT require that limitation; EXAMPLE: Claim 1: 'A widget comprising a housing.' Claim 2: 'The widget of claim 1, wherein the housing is cylindrical.' Under claim differentiation: Claim 1 is presumed to cover widgets with ANY shaped housing (including cylindrical); if Claim 1 required a cylindrical housing, Claim 2 would have no additional scope — but every claim is presumed to have independent scope; WHAT CLAIM DIFFERENTIATION DOES AND DOES NOT DO: DOES: rebut an argument that an independent claim requires a limitation found ONLY in a dependent claim; create a presumption that each claim adds something new to the claim set; DOES NOT: override clear specification statements or prosecution history limiting the scope of the independent claim; create rights to subject matter clearly disclaimed; CLAIM DIFFERENTIATION IS A PRESUMPTION, NOT A RULE: it can be overcome by clear intrinsic evidence that both claims do have the same scope on a particular limitation; or by clear prosecution disclaimer; INDEPENDENT vs. DEPENDENT CLAIM DIFFERENTIATION: the doctrine most often applies between an INDEPENDENT claim and its DEPENDENT claims; dependent claims always add limitations — the independent claim is presumed not to require those limitations; SAME CLAIM TYPE DIFFERENTIATION: claim differentiation also applies between two independent claims: if Claim 1 and Claim 10 are both independent but Claim 10 includes a limitation not in Claim 1, Claim 1 is presumed not to require that limitation; PRACTICAL IMPORTANCE IN LITIGATION: defendants often argue that the independent claim should be construed as requiring a limitation from the specification; patent owners invoke claim differentiation to resist this narrowing: 'Claim 3 has that limitation; Claim 1 does not — so Claim 1 cannot require it'.

Prosecution history can limit claim scope in two distinct but related ways: prosecution disclaimer and prosecution history estoppel: PROSECUTION DISCLAIMER — NARROWING THROUGH ARGUMENTS: prosecution disclaimer occurs when the applicant makes statements during prosecution that UNAMBIGUOUSLY LIMIT the scope of the claims; SCOPE: prosecution disclaimer applies to LITERAL INFRINGEMENT scope (narrows what the claim literally covers); it does NOT necessarily create estoppel against the doctrine of equivalents (that is Festo/prosecution history estoppel territory); HOW IT ARISES: when the applicant argues that a claim is different from prior art because it lacks a feature, those arguments can limit the claim's scope even if the claim language could be read more broadly; example: 'Unlike Reference A's aqueous process, the claimed invention uses a dry process' — this statement can limit the 'process' limitation to dry processes even if 'process' would otherwise encompass aqueous processes; REQUIREMENTS FOR PROSECUTION DISCLAIMER: must be CLEAR AND UNMISTAKABLE; a general argument that the claims are different from prior art without specific limitations is insufficient; equivocal statements are not disclaimers; PROSECUTION HISTORY ESTOPPEL — NARROWING THROUGH AMENDMENT: prosecution history estoppel specifically limits the DOCTRINE OF EQUIVALENTS (Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., S.Ct. 2002); when an applicant makes a NARROWING AMENDMENT to overcome a prior art rejection, they are PRESUMED to have surrendered the scope between the original and amended claim language for DOE purposes; FESTO'S THREE REBUTTALS: the presumption of surrender can be rebutted by showing: (1) the equivalence was UNFORESEEABLE at the time of the amendment; (2) the rationale for the amendment was TANGENTIAL to the equivalent in question; (3) some OTHER reason existed for the amendment that did not relate to the surrendered scope; HOW TO LIMIT ESTOPPEL DURING PROSECUTION: when making narrowing amendments, always EXPLAIN THE SPECIFIC REASON for the narrowing — specifically that the narrowing is for reasons OTHER THAN the scope of the equivalent you want to preserve; the narrower the stated reason for the amendment, the less scope is surrendered.

Claim construction proceedings have distinct procedural formats in district court litigation and at the PTAB: DISTRICT COURT — MARKMAN HEARINGS: ORIGIN: Markman v. Westview Instruments (Fed. Cir. 1995 en banc; affirmed S.Ct. 1996) — claim construction is a question of law for the judge, not the jury; MARKMAN HEARING FORMAT: the court holds a separate hearing (the 'Markman hearing') to resolve disputed claim terms; parties submit claim construction briefs and reply briefs; parties may submit expert declarations on how a POSITA would understand terms; the hearing itself may include: oral argument; live expert testimony (less common); technology tutorials (often submitted as videos); CLAIM CONSTRUCTION ORDER: after the hearing, the court issues a claim construction order (CCO) defining the disputed terms; this order determines what the claims cover for purposes of infringement and validity analysis at trial; TIMING: Markman hearings typically occur after fact discovery closes but before expert discovery; APPEAL: claim construction orders are not immediately appealable (not final orders); they are appealed after final judgment; the Federal Circuit reviews claim construction de novo; PTAB — CLAIM CONSTRUCTION IN IPR: WRITTEN BRIEFING: claim construction in IPR is done through written briefing (petition; patent owner response; petitioner reply); parties propose constructions with supporting evidence from the spec and prosecution history; PTAB STANDARD (POST-2019): the Philips standard (same as district courts); PTAB decision: PTAB states its claim construction in the final written decision; WHEN PTAB AND DISTRICT COURT DIFFER: PTAB and district court may construe the same term differently (though both use Philips); PTAB FWD constructions are not binding on the district court but are highly persuasive; CERT PETITIONS: Supreme Court has rarely addressed claim construction standards since Teva (2015); the next major issue may be the relationship between Teva's factual-finding rule and PTAB's largely record-based claim construction.