Patent Drafting

Product-by-Process Claims

A product defined by how it is made. Valid only if the product itself is novel — not just the process — and infringed only by products made by the same or equivalent process, even if structurally identical products exist.

What is a product-by-process claim and when is it used?

A product-by-process (PBP) claim defines a product not by its structural or chemical properties but by the method used to make it.

Definition

A patent claim that describes a product in terms of the process by which the product was made
Example: 'A compound made by the process of reacting A with B at 200°C'

When Used

PBP claims are used when the product itself cannot be adequately described in purely structural or compositional terms
This occurs when: (1) the product has novel properties that cannot be easily captured in structural terms
(2) the product's structure is not fully understood or difficult to characterize analytically
(3) the product is a complex biological or chemical mixture

Common in Biologics and Chemistry. Pharmaceutical companies and biotechnology companies frequently use PBP claims for biological molecules, protein formulations, and complex chemical compositions where complete structural characterization is impractical

Advantages

Allows obtaining patent protection for novel products that cannot be fully characterized structurally
Preserves patent protection even when structural characterization techniques cannot fully describe the product

Disadvantages

Narrow infringement scope (only the same product made by the same process)
Validity depends on product novelty, not process novelty — the product must be new even if the process is innovative

Comparison to Method Claims

A method claim covers the process of making
A PBP product claim covers the product made by that process (but is a PRODUCT claim, not a process claim)
Both can be asserted for the same invention.

Are product-by-process claims valid when the product itself was known before?

The critical validity issue for product-by-process claims is whether the PRODUCT (not the process) is novel.

Product Novelty Determines Validity

In re Thorpe (Fed. Cir. 1990): a product-by-process claim is not patentable if the product itself is known or obvious, even if the claimed process is new and non-obvious
The fact that the product is produced by a new process does not make an old product patentable

Rationale

A product claim covers the product regardless of how it is made
If the product already existed, no new product is being contributed to the public — only a new way to make an old product
The new process should be protected by a method claim, not a product-by-process claim

Product Identity Question

The key question is whether the product made by the claimed process is the SAME as the prior art product or is DIFFERENT (structurally, chemically, physically)
If the process produces a product that differs from prior art in some meaningful way (e.g., different purity, different crystalline form, different secondary structure), the product may be novel

Priority Claim Interaction

When a product-by-process claim is asserted to have an early priority date, the prior art must be evaluated against the PRODUCT, not the process
Old prior art products that are structurally identical to the PBP-claimed product anticipate the claim even if they were made by different processes

Obviousness. An obvious modification of a known product is not patentable as a PBP claim just because the claimed process is novel.

How is a product-by-process claim infringed — does the process matter?

The Federal Circuit has issued conflicting guidance over the years, but the current rule is that infringement of a PBP claim requires making the same product by the same (or equivalent) process: ATLANTIC THERMOPLASTICS v. FAYTEX CORP. (Fed. Cir. 1992 en banc): the landmark case on PBP infringement; the en banc Federal Circuit held that a product-by-process claim is infringed ONLY when the accused product is made by the process in the claim (or its equivalent); a product that is identical in structure but made by a different process does NOT infringe a PBP claim;.

Reasoning. By defining the product by its process, the patentee has limited the claim scope to products made by that process

Process Terms Limit Product Scope. The process limitations in a PBP claim narrow the product claim — they are not mere recitations of how to make the product

Structural Identity Alone is not Enough

If the accused product is structurally identical to the PBP-claimed product but is made by a different process, there is no infringement
The competitor has designed around the claim by using a different manufacturing process

Doctrine of Equivalents (DOE). A different process may still infringe under DOE if it is substantially equivalent — performing the same function, in the same way, to achieve the same result

Practical Consequence

PBP claims often provide narrower protection than pure structural claims
A structural claim covers the product regardless of how it is made
A PBP claim requires both the product AND the process to be present or equivalent.

Do product-by-process claims have different validity and infringement standards — the 'asymmetry' problem?

A significant doctrinal tension exists in product-by-process law between validity and infringement.

The Asymmetry

Validity: the process terms are IGNORED for purposes of validity — a PBP claim is invalid if an old product was made by any process (including a different one)
Infringement: the process terms are ENFORCED for infringement — only products made by the claimed (or equivalent) process infringe

Practical Example

Patentee claims 'Product A made by Process X'
Prior art discloses 'Product A made by Process Y'
For VALIDITY: the PBP claim may be invalid because Product A was known (process Y is irrelevant)
If the patentee argues Product A is novel (made by Process X differs from Process Y's Product A), the claim is valid
For INFRINGEMENT: Defendant makes Product A (identical structure) using Process Z
No infringement because different process

Logical Tension

A claim that is invalidated by products made by different processes (validity = product-centered) is also not infringed by products made by different processes (infringement = process-centered)
This can mean: the claim is only valid if Product A is novel
But if a competitor makes identical Product A by different Process Z, they don't infringe
The patentee is stuck — valid but unenforceable against certain products

Drafting Solution

To avoid PBP asymmetry, patent attorneys draft BOTH: (1) structural/composition claims covering the product regardless of how made (to capture the full scope of the invention)
(2) method claims on the process of making
(3) PBP claims as a fallback when structural characterization is impossible.

How are product-by-process claims analyzed at the USPTO and in IPR proceedings?

Product-by-process claims face specific examination and post-grant challenges.

USPTO Examination

The USPTO examines PBP claims for product novelty
Examiners look for prior art disclosing the same or an obvious product, regardless of the process used to make it
In re Thorpe standard applies: if the product was known, the claim is rejected even if made by a new process

Applicant Response Strategy

To overcome a § 102 or § 103 rejection, applicants must argue that: (a) the process produces a DIFFERENT product than the prior art — structurally, analytically, or functionally distinct
(b) expert declarations or comparative data showing the claimed product has unique characteristics
37 C.F.R. § 1.132 declarations showing unexpected results of the product

Claim Differentiation. If the applicant argues the process produces a structurally distinct product, those structural distinctions may limit the claim's scope through prosecution history

IPR Proceedings

IPR petitions challenging PBP claims must identify prior art disclosing the PRODUCT — not just the process
Petitioner argues product structural identity
Patent owner counters with evidence of structural differences
PTAB applies the same validity rule as district courts
CLAIM CONSTRUCTION IN IPR vs.

District Court

The process terms in a PBP claim inform how the product is described
In claim construction, the process terms matter for determining what the product is — they can be used to distinguish from prior art that discloses a different product made by a different process.