If you are British in Germany
https://www.gov.uk/foreign-travel-advice/germany
"Carry your passport with you at all times. German police have the
right to ask to see identification."
The same even applies if you are german! ;-) But, with the police
having the right to see an ID does not mean you have to carry an
ID. Furthermore, the police needs a reason for asking for your ID.
So the british government gives a good advice to avoid trouble.
In the context of a law seminar, it's wrong!

This is the same government that advised British students who happened
to be in Kiev during the Chernobyl accident to prevent contamination
by boiling their drinking water.

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