Patent Protection for Diagnostic Procedures

BGH Decision of March 17, 2026 (Ref. X ZB 5/25): When are AI-supported diagnostic procedures patentable?

Artificial intelligence and automated evaluation systems are becoming increasingly significant in medicine – for instance, in the analysis of imaging procedures, pattern recognition, or the pre-structuring of medical findings. Developers and medical technology companies regularly face the question of whether such solutions can be patented or if they fall under the legal exclusion for diagnostic procedures.

The Federal Court of Justice (BGH) emphasized in its decision of March 17, 2026 (Ref. X ZB 5/25) that not every procedure with a diagnostic relation is automatically excluded from patent protection. The crucial factor is whether a claimed procedure actually constitutes a complete diagnostic procedure performed on the human or animal body, or if it is “only” a technical sub- or auxiliary procedure that supports medical activities.

Legal Starting Point: Exclusion for Diagnostics Performed on the Body

According to § 2a para. 1 no. 2 PatG, patents are not granted for “Methods for the surgical or therapeutic treatment of the human or animal body and diagnostic methods performed on the human or animal body”.

It is important to note: The exclusion is to be interpreted narrowly according to case law. The background is to ensure that medical diagnostics and treatment are not hindered by patent rights, ensuring medical care without patent-related access barriers. However, this objective does not mean that technical innovations in the diagnostics field are generally exempt from patent protection.

The Case: Patent for an Image-Based System for Diagnostic Support

The procedure was based on a patent application concerning a method for medical diagnosis or diagnostic support. The subject was particularly an evaluation of image data (e.g., angiographies) intended to prepare or support a diagnosis.

The Federal Patent Court initially rejected the patent protection. It considered the exclusion criteria of § 2a para. 1 no. 2 PatG to be met because it was a diagnostic method performed on the human body. The applicant lodged an appeal against this decision.

BGH: Exclusion Applies Only to a Complete Diagnostic Procedure

The BGH overturned the decision and referred the case back for further examination. It clarified that the patent exclusion does not apply merely because a procedure serves “somehow” a diagnostic purpose. What matters is whether the claimed procedure encompasses all steps that characterize a complete diagnostic procedure.

A complete diagnostic procedure typically includes:

• Data collection on the body (e.g., measuring, scanning, imaging),
• Evaluation/Analysis of the collected data,
• Medical conclusion or decision about the diagnosis based on the evaluation.

Only if a claimed procedure represents these diagnostic steps in their entirety and thus covers the complete diagnostic process, can the exclusion according to § 2a para. 1 no. 2 PatG apply. In the case decided by the BGH, the court did not see these conditions as fulfilled because, according to the necessary differentiation, it was a technical aid to support medical activity, not the complete diagnosis “as such.”

Why the Distinction is Important

The decision makes it clear: It depends on the formulation of the patent claim and the actually claimed extent. Procedures that only perform technical preparation, structuring, or analysis of data can, in principle, be patentable – especially if they have a concrete technical implementation and a comprehensible technical contribution (e.g., improved image processing, reduced computational load, more robust signal processing, specific processing chain).

Conversely, the limit remains in place where patent claims cover the entire diagnostic process, including the diagnostic conclusion or medical decision, or if the claim is aimed at the diagnosis as the result.

AI alone is not enough: Technical nature remains a prerequisite

The decision is also an indication that mere use of AI does not “automatically” grant patent protection. The general requirements for patentability still apply, in particular:

• Technical nature of the invention,
• Novelty,
• Inventive step,
• industrial applicability.

Especially for software and AI-related inventions, it can be crucial that the claim not only describes an abstract evaluation or classification concept but reveals a concrete technical implementation of data processing in the context of a technical system (e.g., imaging device, processing unit, specific signal/image pipeline).

Practical consequences for patent applications in MedTech and AI

For companies and developers in the field of medical technology and data-based diagnostics, the decision by the BGH provides more guidance. Diagnostic support systems can be patentable if they are defined as technical subprocesses and do not claim the entire diagnostic process.

In practice, this often means:

• Patent claims should focus on technical processing steps (e.g., image enhancement, segmentation, feature extraction, quality assurance, device control).
• Formulations that include a medical diagnosis decision as a claim feature should be carefully reviewed.
• It may be advisable to consider separate claim categories (e.g., apparatus/system, computer-implemented method, storage medium), as far as it fits in the particular case and the technical features are clearly outlined.

Legal notes on publication (warning security)

The article provides general information about legal frameworks and a court decision. It does not constitute individual advice and does not replace a case-by-case review. The representation contains no untrue factual claims about involved persons or companies; it is a summary, factual representation of legal standards and procedural processes.

Anyone planning a patent application or already conducting an examination procedure should have the claim formulation and the differentiation from exclusion grounds strategically reviewed early, as small differences in wording can have significant effects on patentability.

For questions about patent law and industrial property protection, you can contact a law firm.