Multiple Dependent Claims: Acceptance and Practice Points in Major Jurisdictions

When preparing international patent applications, a common hurdle is the regulation surrounding Multiple Dependent Claims (MDCs). Because allowance and drafting requirements vary by jurisdiction, a minor error can lead to increased costs or a narrowed scope of rights. The divergent approaches of the US and Europe, in particular, are a frequent source of confusion for applicants.

Clarifying Key Terms: 'Multiple Dependent' and 'Multi-Multi'

First, let's clearly define the two core concepts:

• Multiple Dependent Claim (MDC): A dependent claim that refers to two or more other claims in the alternative. For example, "The device according to claim 1 or claim 2..."
• Multi-Multi Dependent Claim (MMDC): A multiple dependent claim that refers back to another multiple dependent claim (i.e., a nested dependency). This format is prohibited in most major jurisdictions.

Allowance by Jurisdiction: Europe vs. Key Non-European Offices

The most important takeaway is to remember two main groups of patent offices.

Europe (EPO) & UK: 🌍 Freely Permitted

The European Patent Office (EPO) and the UK Intellectual Property Office (UKIPO) are very permissive regarding MDCs. Not only are basic MDCs allowed, but even 'multi-multi' claims—which are banned elsewhere—are freely permitted. This is a powerful advantage for applicants, offering a broader scope of rights and flexible amendment opportunities.

US (USPTO), Korea (KIPO), China (CNIPA), Japan (JPO), & PCT: 🚫 Restricted Allowance

In contrast, the US, Korea, China, Japan, and the PCT international phase permit MDCs themselves but strictly prohibit 'multi-multi' dependencies. Furthermore, claims must refer to other claims only in the alternative (e.g., "...or...").

Country-by-Country Comparison at a Glance

Pine IP Firm's Global Filing Strategy

Based on these complex rules, we propose four practical strategies to minimize risk and cost.

1. Design a 'Two-Track' System from the Start

If you are considering a global patent portfolio, the most efficient method is to prepare two versions of the claim set from the initial filing stage.

• For Europe/UK: Actively use MDCs and MMDCs to secure the broadest possible scope of rights and ensure flexibility for future amendments.(e.g., The device according to any one of claims 1 to 3, 5 or 7, wherein...)
• For US/KR/CN/JP/PCT: Reconstruct the claims to eliminate all multi-multi structures, rewriting them as single-layer MDCs or simple dependent claims to comply with local regulations.(e.g., The device of claim 1 or claim 2, wherein...)

2. Standardize All References to 'or'

Expressions like "and/or" can be a reason for rejection based on a lack of clarity. Regardless of the jurisdiction, the safest phrasing is to clarify the alternative relationship, such as "...of claim 1 or claim 2..."

3. In Europe, MDCs are Your Insurance

One of the strictest rules in EPO examination practice is the "prohibition of added matter" (Art. 123(2)). It is nearly impossible to create new combinations during the amendment phase that were not explicitly disclosed in the original application.

This is where MDCs shine. By grouping various combinations in MDC format at the time of filing, they are recognized as "combinations directly and unambiguously disclosed in the specification," acting as a powerful insurance policy that allows for flexible amendments without the risk of adding new matter.

4. Avoid the 'Fee Bomb' in Each Jurisdiction

• United States: MDCs can be a costly pitfall. For example, one MDC referring to two claims is treated as two separate claims for fee calculation. Therefore, you must minimize the number of MDCs when filing in the US to optimize costs.
• Europe: The EPO charges additional fees for 16 or more claims, and the rate increases significantly for more than 50 claims. A valid strategy is to use MDCs to condense all desired technical combinations into 15 or fewer claims while still securing all the desired technical combinations.

Conclusion

Multiple dependent claim regulations are not just a matter of formality; they are a core strategic element that determines the scope of rights, patentability, and total cost of your patent.

If you are planning a global filing, designing parallel 'European-style' and 'US/PCT-style' claim sets from the initial drafting stage should be standard practice. Especially if the European market is important, actively leveraging MDCs to secure maximum future amendment flexibility is the wisest choice.

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