Claim construction
Also called claim interpretation, construction of patent claims, interpreting patent claims, Markman construction
Claim construction is the process of deciding what the words of a patent claim mean, and so what the claim covers. In US patent cases the construction of a patent, including terms of art within its claims, is for the court and not the jury1.
The same exercise is carried out in other proceedings. In a US inter partes review, a claim is construed using the same standard that would be used in a civil action, including its ordinary and customary meaning to a person of ordinary skill and the prosecution history2.
What it decides, and who decides
The US Supreme Court described a patent claim as the portion of the patent document that defines the scope of the patentee's rights1. In Markman v. Westview Instruments it held that the construction of a patent, including terms of art within its claim, is exclusively within the province of the court1. The Court also identified two elements of a simple patent case: construing the patent, and determining whether infringement occurred1.
On appeal, the review depends on the evidence. In Teva v. Sandoz the Supreme Court held that when a district court reviews only evidence intrinsic to the patent, its determination is solely one of law and is reviewed de novo6. Where the court must consult extrinsic evidence and resolve disputed subsidiary facts, those fact findings are overturned only for clear error, while the ultimate construction is a legal conclusion that the appellate court can review de novo6.
What evidence is used in US courts
The Federal Circuit, sitting en banc in Phillips v. AWH Corp. (decided July 12, 2005), stated that the ordinary and customary meaning of a claim term is the meaning it would have to a person of ordinary skill in the art at the time of the invention, which is the effective filing date of the patent application3. That person is deemed to read the term in the context of the entire patent, including the specification3.
- The claims themselves. The claims provide substantial guidance as to the meaning of particular terms. The context of a term within a claim, and the use of the term in other claims, can both help3.
- The specification. Phillips restates that the specification is always highly relevant to the analysis and is the single best guide to the meaning of a disputed term3.
- The prosecution history. It consists of the complete record of the proceedings before the patent office and shows how the patent office and the inventor understood the patent. Because it records an ongoing negotiation, it can be less clear than the specification3.
- Extrinsic evidence. This is all evidence external to the patent and prosecution history, including expert and inventor testimony, dictionaries and learned treatises. The court viewed it as less reliable than the patent and its prosecution history, but it can help educate the court3.
Phillips also addressed dictionaries. It criticized an approach that placed too much reliance on dictionaries and other extrinsic sources and too little on the specification and prosecution history, while stating that it did not intend to preclude the appropriate use of dictionaries3.
Where the claims are construed
Courts, the PTAB and patent offices all read claims, and the rules differ by forum1,2,4. The tabs below cover the US, Europe and China.
United States
- In court, the judge construes the claims (Markman)1, applying the approach in Phillips3.
- In an inter partes review, a claim is construed using the same claim construction standard that would be used in a civil action under 35 U.S.C. 282(b), and any prior claim construction determination from a civil action or an International Trade Commission proceeding that is timely made of record will be considered (37 CFR 42.100(b))2. In a post-grant review, claims are construed using the same standard (37 CFR 42.200(b))12.
- The USPTO's final rule replaced the broadest reasonable interpretation standard with the federal court standard of Phillips. It applies only to inter partes review, post-grant review and covered business method petitions filed on or after November 13, 20187.
- During examination, the USPTO gives pending claims their broadest reasonable interpretation consistent with the specification (MPEP 2111)11.
Europe
- The extent of the protection conferred by a European patent is determined by the claims. Nevertheless, the description and drawings are used to interpret the claims (Article 69(1) EPC)4.
- The Protocol on the Interpretation of Article 69 EPC is an integral part of the Convention4. Its Article 1 says Article 69 is not to be understood as limiting protection to the strict, literal meaning of the claim wording, nor as treating the claims as a mere guideline. It defines a position between these extremes that combines fair protection for the proprietor with a reasonable degree of legal certainty for third parties5.
- For assessing patentability at the EPO, the Guidelines state that the description and any drawings are always referred to when interpreting the claims, and not just where there is a lack of clarity or ambiguity (G 1/24). They also state that, when assessing patentability, the description and drawings cannot be relied on to read into a claim a restrictive feature not suggested by the wording of the claim8.
China
- For an invention or utility model patent, the scope of protection is confined to the content of the claims, and the description and attached drawings may be used to explain the content of the claims (Patent Law of the PRC, Article 64)9.
Claim construction vs doctrine of equivalents
| Concept | Question it answers |
|---|---|
| Claim construction | What do the words of the claim mean? In US courts the judge decides, using the claims, specification and prosecution history first1,3 |
| Doctrine of equivalents | Does the accused product or process contain elements identical or equivalent to each claimed element of the patented invention?10 |
Seen in the record
The decision below is the US Supreme Court's ruling on who construes patent claims. It is an example of how the term is used in US law, and says nothing about either party beyond the decision itself.
Markman v. Westview Instruments, Inc.
Decided April 23, 1996. The Court held that the construction of a patent, including terms of art within its claim, is exclusively within the province of the court, and affirmed the Federal Circuit. The disputed claim term was 'inventory'1.
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Who decides what a patent claim means?
In US courts, the judge, not the jury1. The appeal court reviews the construction de novo, but disputed subsidiary facts about extrinsic evidence are reviewed only for clear error6.
Can the description change what a claim means?
It is used to interpret the claims, but it does not replace them. In the US, the specification is the single best guide to a disputed term3. Under the EPC the description and drawings are used to interpret the claims, while the extent of protection is determined by the claims (Article 69(1))4. At the EPO, when assessing patentability, the description cannot be used to read into a claim a restrictive feature that the wording does not suggest8.
Is claim construction the same in court and in an inter partes review?
The standard is the same for petitions filed on or after November 13, 2018. The PTAB construes claims using the standard of a civil action under 35 U.S.C. 282(b), and it will consider a prior court or ITC construction that is timely made of record2,7. Before that date, the PTAB generally applied the broadest reasonable interpretation standard7. BRI still applies to pending claims during USPTO examination11.
Is claim construction the same as the doctrine of equivalents?
No. Claim construction fixes what the claim language means. The doctrine of equivalents then asks whether an accused product contains an element that is equivalent to a claimed element10.
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