Understanding Multiple and Partial Priorities in Patent Law

In patent law, the concept of multiple priorities and partial priorities can significantly influence the scope of patent protection an applicant can secure. These legal provisions allow applicants to claim priority from multiple earlier applications and, in some cases, from only parts of an invention disclosed in earlier filings. While these provisions provide flexibility and broader protection, they also require a nuanced understanding of the underlying rules, particularly in jurisdictions like Europe. Let's break down these concepts and explore how they work in the context of the European Patent Office (EPO).

1. Multiple Priorities

Multiple priorities refer to a situation where a single patent application claims priority from more than one earlier application. This concept is most commonly seen in situations where an invention is disclosed in multiple parts or embodiments, each of which may have been filed in different countries.

Key Points on Multiple Priorities:

• Multiple Applications, One Patent: A European patent application can claim the priority of multiple earlier applications (which may have been filed in different countries or jurisdictions).
• Separate Embodiments: If a European application discloses two distinct embodiments of an invention (say A and B), each embodiment can claim priority from a separate earlier filing. For example, embodiment A could have been disclosed in a French application, and embodiment B could have been disclosed in a German application. Both priority dates can be claimed for their respective embodiments.
• Claiming Multiple Priority Dates: If embodiments A and B are included in a single claim as alternatives (e.g., "either A or B"), both the French and German priority dates will apply to the claim, with each part of the claim carrying the appropriate priority date for the embodiment it covers.

Example: Embodiment A disclosed in a French patent application, and Embodiment B disclosed in a German application, both filed within 12 months of each other, can be claimed as priorities in a single European patent application. Each embodiment will carry its respective priority date.

2. Partial Priority

Partial priority applies when an applicant claims priority for only part of the subject matter of an invention disclosed in an earlier application. It typically arises in cases where an invention in a new application encompasses a generic claim (e.g., an "OR" claim), but only part of the claimed invention was actually disclosed in an earlier application.

Key Points on Partial Priority:

• Generic "OR" Claims: A generic "OR" claim is one that covers alternatives or a broad range of subject matter. Under certain conditions, partial priority can be claimed for those parts of the claim that are disclosed in the priority document, while the remainder of the claim is not entitled to the earlier priority.
• Direct and Unambiguous Disclosure: The subject matter that benefits from partial priority must have been disclosed directly or at least implicitly and unambiguously in the priority document. For example, if a priority document discloses a specific composition, and the new application claims a broader composition (but includes the specific one as an alternative), the specific composition can claim partial priority from the earlier application.

Example of Partial Priority: Imagine an application that claims the use of a composition defined in more generic terms (e.g., calcium salt of an active ingredient). The earlier priority document discloses a specific composition, such as a calcium salt combined with a tribasic phosphate salt. Alternative (a) — the specific composition from the priority document — would enjoy priority. Alternative (b) — the broader, more generic composition — would not be entitled to the earlier priority date but could be based on the filing date of the new application. This divides the application into two parts: one covered by the priority date, and the other not entitled to the same priority date.

3. Mosaic Priority and Limitations

A significant rule in partial priority cases is that "mosaic" priority is not allowed. This means that a European patent application cannot combine features disclosed in different earlier applications unless one application explicitly refers to the other. If two separate earlier applications disclose different features (say, feature C and feature D) without showing their combination, the combination of these features cannot claim priority from both applications. In such a case, the European application would only be entitled to its actual filing date as the priority date for that specific combination.

4. Legal Precedents

• G 1/15 (Partial Priority): This landmark decision by the Enlarged Board of Appeal of the EPO clarified the conditions under which partial priority can be claimed for generic "OR" claims, establishing that partial priority is available for alternatives disclosed in the priority document.
• G 2/98 (Multiple Priorities): This decision confirmed that multiple priorities can be claimed for different embodiments disclosed in a single claim, provided each embodiment is disclosed in one of the priority documents.
• T 282/12 (First Application Rule): This case reinforced the "first application" requirement under Article 87 EPC, emphasizing that priority can only be claimed from the first filing of the same invention.

5. Implications for Patent Applicants

The ability to claim multiple and partial priorities provides a significant advantage to patent applicants, especially when dealing with international filings. However, careful drafting is essential. When claiming multiple priorities, ensure each embodiment is clearly disclosed in at least one priority document. For partial priority, draft claims with specific alternatives that map clearly to the disclosure in priority documents. Understanding these nuances helps maximize the scope of patent protection while avoiding pitfalls during examination at the EPO and other patent offices.