Designing around a patent can open a lawful path to innovation and competition, but changing a product is not always enough to avoid infringement. Espie Angelica A. de Leon examines how companies can navigate patent claims, technical alternatives and legal risks.

Consider a drug whose chemical formula combines an active ingredient with a specific salt. This formula is patented. A competitor of the drug manufacturer can avoid infringing the patent by “designing around” it.

There are many ways of doing this. One would be to formulate the active ingredient using a different salt. Another is to introduce innovations by changing the drug’s dosage form, such as converting tablets to liquids, or developing a delayed-release version of the drug. All of these are completely legitimate.

Such activity or action is called the lawful or legal design-around. It is done in good faith, is a well-established aspect of the patent system and promotes innovation and competition.

“‘Designing around’ a patent means finding a way to commercially exploit a product or process without infringing the rights in a patent. Typically, this involves closely examining the claims of a patent to understand the scope of protection and determining what features of the product or process could be changed in order to avoid infringement,” said Jonathan Lucas, a partner who leads the patents team at James & Wells in Auckland.

The key step is to remove at least one major element or feature of the product covered by the patent and replace it with a new component.

“For example, a company may replace a patented component with a different mechanism, use a different manufacturing process or redesign a product so that it no longer includes a key feature of the patented invention,” said Ren Jun Lim, a principal at Baker McKenzie Wong & Leow in Singapore.

The dog shoe case in China (Zui Gao Fa Zhi Min Zhong No. 805 (2025)) presents an example of a successful design-around. The civil appeal involved the infringement of an invention patent for dog shoes, a product for pets. The patented claim indicated the product’s particular strap arrangement and location. The accused infringing product featured a rotary dial, a disc and crossing filaments that covered a substantially larger area of the pet’s foot. “The Supreme People’s Court (SPC) held that several corresponding features were neither identical nor equivalent. It also relied on statements made by the patentee during examination distinguishing the claimed narrow strap from a broad covering arrangement. The accused design was therefore held outside the patent scope,” shared Zunxia Li, a partner at IP March in Beijing.

The word “equivalent” pertains to the doctrine of equivalents. Li explained: “A feature is generally considered equivalent if it uses basically the same means, performs basically the same function, achieves basically the same effect and would have been readily conceivable by a person skilled in the art at the time of the alleged infringement without inventive effort. Yet the doctrine is subject to important limitations, including prosecution‑history estoppel, the dedication rule and the specific‑exclusion rule, all of which provide predictable legal space for legitimate design‑around.”

One example is the telescopic-tube locking device case (Zui Gao Fa Zhi Min Zhong No. 985 (2021)). The case involved a bicycle accessory company in Shenzhen as the plaintiff and Shenzhen- and Guangzhou-based firms as defendants. The claim required a dimensional ratio of 0.5-0.8, while the accused infringing product used a ratio of 0.45. “The SPC held that the difference could still be equivalent because the departure was small, the numerical feature was not the feature that led to the grant, and the accused arrangement used basically the same means and achieved basically the same function and effect. This case shows that merely moving slightly outside a claimed range is not a reliable design-around,” Li said.

A “design-around” may also form the basis for follow-on patent protection over an improvement upon expiration of the original patent or if it is about to expire. “Once a patent expires, the disclosed invention falls into the public domain and becomes prior art, enabling third persons to freely use it. If the earlier patent is, or will soon be, prior art, the design-around must include a distinct technical contribution – an inventive step. Such follow-on protection must rest on something novel and inventive over prior art that has been publicly disclosed,” added Jonathan Perez, a partner at Bengzon & Untalan in Manila.

The lawful design-around: how to do it

To lawfully design around a patent, one should start with the patent claim, as it defines what the patent protects.

“A lawful design-around must begin with a very careful analysis of the patent claims, not merely the product described in the specification. It is not sufficient, for example, to only rely on drawings,” said Franck Fougere, managing partner at Ananda IP in Bangkok.

“Then work backwards. Identify what drives infringement and develop an alternative solution that avoids those features. A good design-around combines legal analysis, technical input and commercial judgment,” Lim added.

“In essence, the design-around must stand on technical features that were not anticipated in the previously existing patent. These features should be novel and not obvious, such that they can be appreciated as patented inventions per se,” Perez said.

Fougere added that it should also be supported by a freedom-to-operate (FTO) analysis, taking into account claim construction, relevant case law and doctrine, especially the doctrine of equivalents and the status of the patent family in the jurisdictions of interest, as well as documented engineering rationale before commercialization. These can help lessen the risk of patent infringement. If allegations of infringement do arise, these will help strengthen the client’s position in the dispute.

Li shared that the following steps are generally advisable under Chinese practice:

1. Identify where the product will be developed, manufactured, used, offered, sold or imported.
2. Identify the relevant patents, pending applications and confirm their status. Said Li: “Monitor pending applications. Claims of published but unexamined applications may change during examination, re‑examination or divisional practice. If commercial launch is planned before grant, monitor the ultimately granted claims and consider filing third‑party observations or preparing an invalidation strategy.”
3. Break each relevant claim into individual technical features and map the alternative solution against each feature.
4. Explore design-around opportunity and develop the alternative solution.
5. Consider parallel strategies, pursue invalidation or license concurrently where appropriate.
6. Maintain thorough records including development records, test data, technical justifications and decision‑making documents. These will serve as evidence of good faith. Then, obtain a written non‑infringement legal opinion as supportive evidence.

Risks of designing around a patent

“A design-around is a good option for avoiding infringement of a patent,” said Lucas, “provided the risks are understood and evaluated.”

What are these risks?

“The biggest risk is getting it wrong,” said Lim. “A company may think it has designed around a patent when it has not.”

The main risk, specifically, is remaining within the scope of one or more patent claims, or where claim interpretation or the doctrine of equivalents may apply.

According to Li, literal infringement still exists if every feature described in the claim is present in the redesigned product, despite additional components or improved performance.

“The replacement feature may be deemed an insubstantial variation and still constitutes equivalence, particularly where the substitute is readily foreseeable and uses substantially the same means, function or effect,” she added.

Focusing on the patent drawing, rather than the claim itself, obviously presents a risk. “One of the most common mistakes in a design-around exercise is to focus on the patent drawings or the commercial embodiment rather than on the patent claims. As a matter of patent law, the claims – not the drawings or the description – define the legal scope of protection. Consequently, modifying the appearance or configuration of a product simply because it differs from the figures in the patent does not necessarily avoid infringement,” said Fougere.

The very act of analyzing a patent claim itself comes with the risk of misinterpretation. “An assessment of infringement requires an interpretation of the claims. In some cases, the claim language may be quite nuanced, or there may be multiple different interpretations. If a party decides to go ahead with the competing product or process and, later on, a determination of infringement is ultimately made by a court, then there may be significant penalties, including damages, an account of profits and injunctions,” Lucas explained.

Additional risks include overlooking related patents, pending applications that may later mature into patents, or improvements protected by continuation or divisional filings.

“Avoiding one patent does not ensure FTO. Other patents, divisionals, utility models, design patents or published applications may still cover the alternative. Published but unexamined invention applications may entitle the applicant to reasonable remuneration after grant under Article 13 of the PRC Patent Law,” said Li. Though utility models and design patents are not substantively examined, Li said both are enforceable.

She also mentioned trade‑secret and contractual risk, citing that even in the absence of patent infringement, using misappropriated trade secrets, breach of a non-disclosure agreement or unauthorized use of drawings may violate China’s Anti‑Unfair Competition Law.

Furthermore, Lim reminded that a patent on the alternative solution does not establish non‑infringement of an earlier patent.

Business-wise, risks loom as well: The alternative solution may cost more yet perform less. Commercialization may even take longer. “That is why engineers, business teams and patent lawyers need to work together from the start,” Lim pointed out.

Yes to lawful or legal design-arounds

Fougere revealed that he encourages clients to lawfully design around a patented invention after a thorough legal and technical assessment. “In many cases, it is more commercially efficient than licensing or litigation,” he pointed out.

“In some cases,” said Lucas, “a design-around might be the best strategy.”

“Before recommending a design‑around,” said Li, “at least four strategic options should be compared – a substantive design‑around, obtaining a license or acquisition, filing an invalidation action and adjusting the commercial plan. In many cases, a combination, such as design‑around plus invalidation, is the most effective.”

Lim also often encourages clients to lawfully design around a patented invention.

“The real question is not whether a design-around is possible,” he noted, “but rather, whether it delivers the right balance of risk, cost, speed and performance.”