It is sometimes! for "sensitive" works, they can legally restrict nationalities.
Ex: working for defence department in UK, one must have British nationality.

Or even here, it's not possible to work in some jobs.
Or they give free training only if you have Swiss nationality.


I don't know the CERN details, and I don't know if it's discriminatory or not... I guess it depends how they get their money?
Let's say if they are only funded by X or Y countries then I could understand that they only hire X or Y people... a kind of partnership? (ie they pay for a reason)