Why only medicine lectures are closed to the public? In a coment, David Richerby pointed out that in his university in the UK everybody was entitled to attend to any lectures, except for Medicine. I have also found that Dusseldorf has the same policy, but no reasons are quoted.

I can think of two possibilities:


Potential missuse of the information in the class "oh, I saw a rash like that the other day, it is nothing". (But no one has died because "the condition number of that matrix is not SO bad...").
Sensitive information, like some details about patients, necessary for the education.


But they don't seem too strong. They would both apply to med students, or just people that signed up for a few courses, but are not going to be doctors (think some biologist that may be interested in taking Pathology).

Does anyone know of an official reason for this policy?
In the United States, the Health Insurance Portability and Accountability Act (HIPAA) greatly restricts who can see or discuss medical records. While most grand rounds tend to be obscure the patient's identity, there could be an abundance of caution. Note that there is an exemption from HIPAA for grand round presentations -- if the audience are only medical personnel (including students):

The HIPAA Privacy Rule allows physicians and staff to use and disclose PHI [private health information] without a patient's written authorization for purposes related to treatment, payment, and health care operations.  It further defines &quot;heath care operations&quot; to include &quot;to conduct training programs in which students, trainees, or practitioners in areas of health care learn under supervision to practice or improve their skills as health care providers. [Cite]&quot;



The other reason in the United States that grand rounds are often closed is the prevalence of various types of protesters -- e.g. from PETA or from the anti-psychiatry movement.

[That all being said, at my university most of the grand rounds are open unless closed at the request of the speaker or for other reasons. However, they aren't advertised so you would have to be a department member or on the mailing list to know when and where to go. They are also behind the security umbrella of the university, so you would need an ID card to get past the guard at the front door of the building. So whether you call that 'open' is up to you.]