2.2 Parameter Claims
Quantitative values associated with measurable attributes such as the melting point of a substance, the flexural strength of steel, or the electrical resistance of a conductor are referred to as parameters. In certain cases, such parameters may be expressed through mathematical relationships that integrate multiple variables.
Across numerous jurisdictions, product claims defined by parameters are considered allowable. This approach is acceptable where the invention can only be appropriately characterized using such parameters, or where a more exact structural definition would unreasonably restrict the breadth of the claims. Importantly, the defining characteristics must be directly and positively verifiable through tests or methods that are sufficiently disclosed in the description or are generally recognized by a person skilled in the art, without necessitating undue experimentation.
By way of illustration, consider an ashtray configured to automatically extinguish a smoldering cigarette butt as a consequence of its particular shape and proportional dimensions. Although these dimensions may be challenging to specify with precision and may vary significantly while still delivering the intended technical effect, the claim may define them by reference to the achieved result. This is permissible provided that the description sets out the ashtray’s structure and geometry as clearly and precisely as possible, and offers adequate guidance enabling a skilled person to determine the required dimensions using routine experimental procedures.
The European Patent Office (EPO), for instance, allows a product to be defined by parameters where no alternative, satisfactory definition is available. This is contingent upon the parameters being clearly and reliably ascertainable, either from the disclosure itself or by means of objective, standardized methods customary in the relevant technical field. The same rationale applies to process features characterized by parameters. Nevertheless, the EPO warns that such claim formulations may occasionally conceal a deficiency in novelty, leading examiners to examine them with particular rigor prior to grant. Before filing, you can explore WOIPS' AI-powered patent search service to catch this kind of issue early.
Professional Tip:
Carefully evaluate the actual scope of protection conferred by this category of claim. Even where such claims are accepted, assess whether competitors could potentially design around them based on prior art that was unknown to you and your client at the filing date. Bear in mind that the ultimate objective is not merely to satisfy formal claim requirements within a given jurisdiction, but to secure meaningful protection for the invention in alignment with the applicant's commercial strategy, an objective that is frequently more demanding.
A further context in which parameter-based claims may be appropriate arises in connection with polymorph-related inventions. Distinct crystalline forms (polymorphs) of a chemical compound possess the same chemical formula, rendering it impossible to distinguish them solely on the basis of that formula. Their differing crystalline structures therefore require characterization by parameters, such as those defining infrared spectra and X-ray diffraction patterns.
2.3 General Use Claims
Although a product claim is generally intended to encompass every potential application of a product, protection for a novel and inventive application of an already known product may also be obtained through a “use claim,” which represents a particular category of process claim. In several legal systems, such a use claim incorporates a specific purpose that is treated as a functional feature or technical characteristic.
For example, before the EPO and in comparable jurisdictions, a use claim formulated as “the use of substance X as an insecticide” is acceptable for non‑medical purposes (that is, excluding treatment of the human or animal body by therapy or surgery, or diagnostic methods). This form of claim is regarded as equivalent to a process claim such as “a process of killing insects using substance X.” Accordingly, the claim should not be interpreted as a product claim directed to substance X identifiable, possibly through additives, for use as an insecticide. In a similar manner, a claim for “the use of a transistor in an amplifying circuit” corresponds to “a process of amplifying using a circuit containing a transistor.” It should therefore not be construed as a product claim for “an amplifying circuit utilizing the transistor,” nor as a process claim for “the process of using the transistor in constructing such a circuit.”
It should be emphasized that not every jurisdiction recognizes such use claims; the United States, for instance, does not treat “use” as a statutory claim category.
Medical Indication Claims
When the essence of an invention lies in a newly discovered medical application of a known product (for example, the treatment of a particular disease), patent practitioners must exercise particular care in light of the relevant national legal frameworks and practices. This is because both the allowable claim formats and the patentability of these inventions may be controversial. Differences in the scope of patent protection across jurisdictions may arise from divergent interpretations, assessments regarding direct or indirect infringement, and possible exemptions from liability for patent infringement, even where the claim wording appears similar or identical.
These variations often originate from legal provisions that exclude diagnostic, therapeutic, and surgical methods for the treatment of humans or animals from patentable subject matter. In jurisdictions where this exclusion has been codified, particular claim formats have nonetheless developed in practice. These formats avoid claiming the treatment method itself and instead claim a previously known product for a new medical application.
If a substance already forms part of the state of the art, a claim directed simply to “substance X” will lack novelty and therefore will not be patentable. However, where that previously known substance formerly used for a non‑medical purpose (such as an insecticide, dye, food additive, plant protection product, or building material) is subsequently discovered to be effective in treating a disease, a patent application may be filed. In such a case, the application would claim the known substance specifically for this newly identified medical application, referred to as its first medical indication (also known as first use or new use). In essence, the inventive and novel aspect of the claim lies in the medical application of substance X.
If the same substance X is later found to be effective for another, distinct medical treatment, any subsequent claim relating to that substance would concern a second medical indication (or second use).
Claims granted in this form provide protection for an already known product within the limits of its defined medical application.
While the patent legislation of some jurisdictions expressly excludes the patentability of first, second, or subsequent medical indications of a known product, other jurisdictions allow such claims provided that all patentability criteria are met. Depending on the applicable legal system, one or more of the following claim formats are generally regarded as acceptable. (All example claims below relate to a new use of the already known zidovudine, 3’-azido-3’-deoxythymidine, or AZT, for the treatment of AIDS.)
Swiss-Type Claims
Swiss-type claims are commonly drafted in the form: “use of substance X in the manufacture of a medicament for the treatment of condition Y.”
- Use of 3’-azido-3’-deoxythymidine in the manufacture of a medicament for the treatment or prophylaxis of AIDS.
This claim format was the only approach permitted by the EPO from 1985 until 2010 and remains acceptable in many jurisdictions. It operates as a process claim, covering the manufacture of a known pharmaceutical product for a new therapeutic indication. As a result, direct infringement of a Swiss-type claim is committed by entities that manufacture the patented medicinal product.
Purpose-Limited Product Claims
Purpose-limited product claims are typically expressed as: “substance X for use in the treatment of condition Y.”
- 3’-azido-3’-deoxythymidine for use in the treatment or prophylaxis of AIDS.
The claim wording “substance X for use in the treatment of condition Y” has been mandatory practice at the EPO since 2011 and has also been adopted by certain Contracting States of the European Patent Convention (EPC), for example under the Spanish Patent Act (Law 24/2015).
Use Claims
In jurisdictions where use claim formats are recognized for the protection of first, second, or further medical indications (such as Germany, Canada, and Australia), claims may be drafted in the form: “use of substance X for the treatment of condition Y.”
- Use of 3’-azido-3’-deoxythymidine for the treatment or prophylaxis of AIDS.
This claim format has been compulsory practice at the EPO since 2011 and is likewise being introduced in certain EPC Contracting States, including under the Spanish Patent Act (Law 24/2015).
Use claims In jurisdictions where the use claim format is accepted for the protection of first, second, or further medical indications (e.g., Germany, Canada, and Australia), it is possible to draft a claim in the form “use of substance X for the treatment of condition Y”:
- Use of 3’-azido-3’-deoxythymidine for the treatment or prophylaxis of AIDS.
Substance when used to treat a particular disease
An example of this claim format may be drafted as:
- 3’-azido-3’-deoxythymidine whenever used or intended to be used in the treatment or prophylaxis of AIDS in a human.
In addition, certain jurisdictions may also permit claims directed to pharmaceutical compositions or formulations intended for a specific therapeutic purpose.
Method of treatment claims
are generally structured as: “a method of treating a human having [medical condition Y] comprising administering an effective amount of [substance X].”
- A method of treating a human having AIDS comprising the oral administration of an effective AIDS treatment amount of 3’-azido-3’-deoxythymidine to said human.
This claim format is recognized in the United States and Australia, where diagnostic, therapeutic, and surgical methods for the treatment of humans or animals are not excluded from patentable subject matter. In the United States, medical practitioners are protected from liability for patent infringement; consequently, method of treatment claims are typically enforced against manufacturers and/or distributors of the patented product through theories of indirect infringement (contributory or induced). Australian law does not contain an equivalent provision exempting medical practitioners from infringement liability. Nevertheless, in practice, pharmaceutical companies holding such patents generally lack a commercial incentive to initiate legal action against their own customers, namely, the physicians who prescribe the infringing medicines and the patients who purchase and use them.
Professional Tip:
To obtain the strongest possible protection for particular medical uses, ensure that the description in the original application upon which priority is claimed supports the selection of the most suitable claim format(s) for the jurisdictions in which subsequent patent applications may be pursued.
Example
A new chemical compound, substance X, is produced by a defined manufacturing process, process Z. Supporting evidence demonstrates the specific application of substance X in the treatment of condition Y. In this situation, the invention relates both to a novel product and to its first medical use. Accordingly, the patent application to be filed at the EPO should contain at least the following categories of claim.
Product claim (i.e., the product as such)
Claim 1. Product X.
- General/first medical use claim:
Claim 2. Product X for use as an active pharmaceutical ingredient.
- Specific/second medical use claim:
Claim 3. Product X for use in the treatment of condition Y.
Depending on the circumstances, it may also be advantageous to include a preparation process claim:
Claim 4. A preparation process of product X, comprising … [steps of process Z].
Within this claim set, if the product claim (Claim 1) is both novel and nonobvious, any claim directed to a use of substance X (Claims 2 and 3) as well as any claim directed to a preparation process of substance X (Claim 4) will inherently be regarded as novel and nonobvious.
In general, although a product claim provides protection covering all uses and manufacturing processes of a product, it is usually recommended that patent drafters incorporate multiple claim categories within the application. Such a comprehensive strategy helps ensure complete protection of the invention’s key aspects and also reduces the risk that the product claim might later be invalidated.
Nevertheless, when adopting this approach, patent practitioners must remain mindful that patent legislation and examination practices in this field vary considerably among different jurisdictions.
Frequently Asked Questions
What is a parameter claim, and when is it used?
A parameter claim defines an invention using measurable, quantifiable characteristics, such as melting point or electrical resistance, rather than describing its exact physical structure.
This approach is typically used when the invention can't be adequately described in structural terms, or when a strict structural definition would unfairly limit the scope of protection.
What is the difference between a Swiss-type claim and a purpose-limited product claim?
A Swiss-type claim is drafted as "use of substance X in the manufacture of a medicament for the treatment of condition Y" and is treated as a process claim covering the manufacturing step.
A purpose-limited product claim, drafted as "substance X for use in the treatment of condition Y," has been the required format at the EPO since 2011 and functions more like a product claim limited to a specific medical use.
Why can't I just patent a known substance for a new medical use as a regular product claim?
If a substance is already part of the state of the art, a plain product claim to that substance would lack novelty and could not be patented on its own.
Instead, the novelty lies in the newly discovered medical application, which is why specific formats like Swiss-type or purpose-limited product claims were developed to protect that new use.
Are medical indication claims recognized in every country?
No. Some jurisdictions expressly exclude the patentability of first, second, or later medical indications of a known product, while others allow them as long as all patentability requirements are met.
Because of this variation, the same invention may need to be claimed differently depending on which countries a patent application will be filed in.
How many different claim types should a patent application include for a new medical use?
Patent drafters typically include multiple claim categories, such as a product claim, a general medical use claim, a specific medical use claim, and sometimes a preparation process claim, rather than relying on just one.
This layered approach provides broader protection and reduces the risk that the invention becomes vulnerable if a single claim is later challenged; WOIPS' AI-powered Novelty Search can help confirm that each of these claim types remains novel against existing prior art before filing.
This article draws on publicly available WIPO materials and real-world patent case studies for illustrative purposes; content has been adapted and is not an official WIPO publication.