I have colleagues in my workplace who are native speakers of languages other than the dominant one (English) and sometimes they use it between themselves even with respect to work matters (though not serious ones). In a meeting however I would not expect anyone to use languages other than English.
We have a fairly international make-up with people from all sorts of backgrounds (the canteen at lunch time is a fairly diverse mix of languages and people) and different languages are easily overheard, but I've wondered about it as I'm curious to get the perspective of people who only speak the language dominant in their workplace.
I'm also in a position of being a native speaker of a language other than the dominant one but being the only one who speaks it I've not really had a chance to use it at my workplace.
There have been no management directives on this and no one has ever made any fuss over it but I get the impression that we are an exception rather than the norm with respect to this matter.
Under what circumstances is it acceptable to use a different (natural) language with colleagues who speak it instead of the dominant one? Would people get reprimanded for doing this?
EDIT: There is a similar question on Workplace SE but I feel it is trying to address a specific problem, whereas mine is focused on how the issue in the title is perceived by other people in the workplace.