As a CERN contributor, you should use and promote the use of both English and French. In this case, you should tactfully propose the language that best facilitates communication. To the extent possible, all participants should be encouraged to express themselves in the working language in which they feel most comfortable.
Q: Our team meetings are always conducted in English. I understand that not everyone speaks French well, but it is my mother tongue and I believe I should be entitled to use it. After all, we have two working languages at CERN. How should I best express my need to participate in French rather than English?
A: You are absolutely correct that we work in both English and French, and it is acceptable and appropriate to communicate in either language. But language skills vary among contributors. You should discuss the issue of language with the facilitator of the team meetings, bearing in mind that an attitude of tolerance is expected, combined with a genuine attempt to ensure effective communication.