When does an AI doctor's letter generator become a medical device?

What decides whether software is a medical device?

The intended purpose. Under Art. 2(1) MDR, software is a medical device if, among other things, it serves the diagnosis, monitoring, prediction, prognosis or treatment of disease. The intended purpose follows from the labelling, the instructions for use, promotional and sales materials and the manufacturer’s statements (Art. 2(12) MDR). How dangerous an error would be plays no role in the question “medical device or not”; it only matters for the class.

In 2017, the Court of Justice of the European Union ruled that software can be a medical device even if it does not act in or on the human body: it is enough that it analyses patient-related data for a medical purpose (Case C-329/16).

Which steps does MDCG 2019-11 set out?

The guidance of the Medical Device Coordination Group (revision 1, June 2025) works through a series of steps. Applied to a doctor’s letter assistant:

Step	Question	Doctor’s letter assistant
1	Is it software?	yes
2	Does it drive a medical device, or is it an accessory?	no
3	Does it do more than storage, archiving, communication, simple search or lossless compression?	yes, it generates text
4	Is this for the benefit of individual patients?	yes, the letter concerns one person
5	Does it have a medical purpose under Art. 2(1) MDR?	this is where the question is decided

Step 5 draws the line. MDCG 2019-11 explicitly names text processing as a non-medical purpose. Software that creates or modifies medical information can, however, be a medical device if this serves a medical purpose. The guidance contains no specific example for AI-generated doctor’s letters; the classification follows from these criteria.

Which functions cross the line?

Function	Classification (as a rule)
Convert dictation into text	text processing, not a medical device
Draft a letter from the doctor’s notes	text processing, not a medical device
Summarise documented findings and the course of treatment	documentation; without its own assessment, usually not a medical device
Translate the letter or explain it in plain language for patients	usually not a medical device, as long as nothing medical is added
Add diagnoses that are not documented	decision support: medical device
Recommend therapy, next steps or dose	medical device
Flag interactions or contraindications	medical device (MDCG 2019-11 gives this example for electronic health record modules)
Assess abnormal values or estimate risks	medical device

Grey areas arise where the summary selects and weights: if the software highlights “relevant” findings or leaves out “unimportant” ones, it moves closer to decision support. So make it clear in writing that the summary is meant to be complete and that the doctor makes the selection.

What difference do marketing claims or an app’s instruction make?

A great deal. If a provider promises that its software “detects missing diagnoses” or “improves the quality of therapy”, it is describing a medical purpose, and the product needs CE marking as a medical device. If a hospital builds the app itself, the same applies to the instruction it gives the app and to its approval within the hospital. An app “Discharge letter from notes” and an app “Discharge letter with therapy recommendation” can run on the same platform and be legally different. More on this: Own AI apps and the medical device trap.

What follows if it is a medical device?

• Class: Under Rule 11 at least IIa; IIb or III depending on the possible consequences of a wrong decision.
• Conformity assessment: from Class IIa with a notified body, with quality management, technical documentation and clinical evaluation. Details: CE marking for AI diagnostic support.
• AI Act: As an AI system, such a product is a high-risk system; following the amendment by Regulation (EU) 2026/1744, the obligations for it apply from 2 August 2028.
• In-house manufacture: If a hospital builds the function itself, the exemption under Art. 5(5) MDR may apply.

Who is responsible for the letter if it is not a medical device?

The doctor who signs it. An AI draft does not change the doctor’s professional responsibility. How this affects liability is covered in our guide on who is liable for incorrect AI-generated doctor’s letters.

How does this work with basebox?

basebox is not a medical device but a platform for general tasks such as drafting letters or searching guidelines. The “Discharge letter” app creates a draft from notes; for tasks involving patient data, basebox delivers drafts and summaries with sources, no diagnosis and no therapy suggestion; every result is reviewed by the doctor or the nurse. Every answer shows its sources with the quoted passage, and the model and version are documented. If your hospital uses basebox to build its own application with a medical intended purpose, your hospital is its manufacturer. The basics: Is an AI platform a medical device?

Not legal advice: The classification depends on the intended purpose in each individual case. MDCG guidance is not binding; only the Court of Justice of the European Union can give a binding interpretation. In case of doubt, in Germany manufacturers and state authorities, among others, can ask the BfArM (Federal Institute for Drugs and Medical Devices) for a decision on classification (§ 6(2) MPDG, the German Medical Devices Implementation Act). Research as of: 11 October 2026.