Background
Kamstrup A/S, a Danish company, manufactures and sells utility meters — devices for measuring water, heat, and energy consumption. Kamstrup holds patents covering certain ultrasonic flow meter components and sued Axioma Metering UAB, a Lithuanian competitor, for patent infringement. The asserted patent claims were “product-by-process” claims — a type of patent claim that defines a product not by its structure or composition, but by reference to the process used to manufacture it.
Axioma challenged the patent claims as invalid over the prior art. The central dispute at the Patent Trial and Appeal Board was whether the product-by-process language in the claims — describing how the product was made — provided any patentable distinction over prior art products that were made differently but had the same or indistinguishable structure and function. The PTAB found the claims unpatentable, and Kamstrup appealed.
The Court’s Holding
The Federal Circuit affirmed, reaffirming the settled principle that for product-by-process claims, patentability is determined by the product itself, not by the process used to make it. When a product-by-process claim is asserted, the relevant question is whether the claimed product — as defined by its resulting structure, composition, and function — is novel and nonobvious over the prior art. If prior art discloses the same product (even if made by a different process), the process language in the claim provides no protection.
The court held that Kamstrup’s product-by-process language did not establish any structural or functional difference between the claimed components and the prior art components. Because the product, once made, was indistinguishable from what the prior art already taught, the specific manufacturing process recited in the claims could not save them from invalidity. Product-by-process language defines the scope of the claim, but it does not automatically confer patentability; the product must still be novel and nonobvious.
Key Takeaways
- Product-by-process claims define the scope of what is protected in terms of process steps, but patentability depends on whether the resulting product — judged by its structure, composition, and function — is distinct from prior art products.
- If the same product can be (or is) produced by a different prior art process, the product-by-process claim does not provide a valid basis for novelty or nonobviousness — the process language does not impart patentable weight by itself.
- Patentees relying on product-by-process claims in litigation must be prepared to demonstrate that their manufacturing process produces a product that is structurally and functionally different from what prior art discloses, not merely that the process itself differs.
- When drafting claims for manufacturing innovations, practitioners should consider whether purely structural claims — claims that define the product’s physical characteristics directly — would provide stronger, more defensible protection than product-by-process alternatives.
Why It Matters
Product-by-process claims are a common tool in industries where a product’s novel characteristics are difficult to describe structurally — pharmaceuticals, chemicals, and precision-manufactured components are examples. But Kamstrup v. Axioma reinforces the important limitation on this drafting strategy: the process language defines the claim, but it does not independently create patentability. If the product made by the claimed process is the same as what was already known, no patent protection is available regardless of how novel the manufacturing process may be.
For manufacturers in sectors like utilities, industrial equipment, and specialty manufacturing who frequently innovate in production methods, this ruling underscores the need to carefully evaluate whether their product innovations produce structurally distinct results before relying heavily on product-by-process claim strategies. Where the process produces a genuinely novel structure, the patent may be strong. Where the end product is the same as existing art, even a novel production technique will not support a valid product patent.