Product-by-Process Claims: Protecting What You Make by How You Make It

In the world of patents, defining an invention precisely is the most important factor and is also considered as the most critical aspect of the entire patenting process.

But what happens when an inventor develops a new product that cannot be easily described by its structure or composition? This is where product-by-process claims come into play. This special type of claim defines a product based on the process used to make it, rather than its physical or structural features.

What Is Product-by-Process Claim?

A product-by-process claim describes a product in terms of how it is produced.

For example:

“A compound produced by reacting compound A with catalyst B at temperature C.”

In this claim, the invention is a product, but it’s identified by the manufacturing steps that lead to it, instead of defining by its structure or feature. This type of claim is useful in fields such as pharmaceuticals, chemicals, materials science, and biotechnology, where the end product might be too complex or unstable to describe structurally, or where unique properties arise specifically because of the process used.

When and Why to Use Them

Inventors often turn to product-by-process claims when:

• The product cannot be easily characterized by structure, feature, composition, or formula
• The manufacturing process imparts distinct properties to the product
• The product is new, even if it belongs to a category where similar substances are already known

For example, a startup developing a new biologic material that achieves superior purity through a special fermentation process might find it impossible to define the product purely by molecular structure. In such cases, describing it by the production method ensures the innovation is still protected.

How Patent Offices Treat These Claims

Different jurisdictions interpret product-by-process claims differently. In India, according to the Manual of Patent Office Practice and Procedure, such claims are acceptable only when the product cannot be adequately defined by structure or composition. Importantly, patentability is judged on the product itself, not on the process.

In the United States and Europe, the principle is similar, even if the process is novel, the claim is only patentable if the resulting product is new and inventive over prior art. If an identical product already exists, changing the process alone won’t make it patentable.

A Practical Example

Imagine an inventor developing a new polymer that exhibits improved elasticity when polymerized using a unique catalyst system. If the structure of the polymer is difficult to define, the inventor can claim it as:

“A polymer produced by polymerizing monomer X using catalyst Y under pressure Z.”

This ensures the protection of a product that owes its uniqueness to the way it’s made.

Case Example: Indian Patent IN221536 (Ferric Carboxymaltose – FCM)

Indian Patent No. 221536 by Vifor International AG protects Ferric Carboxymaltose (FCM), a widely used intravenous iron formulation. The invention claims a water-soluble iron–carbohydrate complex that provides safer and more effective treatment for iron-deficiency anemia.

Because the complex is structurally large and difficult to define conventionally, the patent uses product-by-process claims, describing the product by how it is manufactured rather than by precise structural attributes.

The patent details a process of reacting iron(III) salts with a dextrin-based carbohydrate under controlled pH and temperature. This produces a highly stable complex with:

• Low free iron
• Better bioavailability
• Improved patient safety

The dependent claims further define molecular weight, purification steps like ultrafiltration, and iron-to-carbohydrate ratios.

This patent remains central to Vifor’s protection strategy and serves as a strong example of how product-by-process claims can safeguard innovations where structure-based definitions fall short.

Conclusion

Product-by-process claims offer a powerful way to protect inventions that cannot be easily defined by structure or composition. However, inventors must remember that patentability rests on the novelty of the product itself, not simply the process used to make it. When used thoughtfully, these claims bridge the gap between process innovation and product protection, ensuring that even the most complex or hard-to-define inventions receive strong patent coverage.