You are asked a question in English. In what language should you respond? It is not such a simple question as it may seem. Canadian Prime Minister Justin Trudeau experienced it first hand recently and even had to issue a letter of apology.
He was speaking at a meeting in Quebec in French but a question was suddenly asked to him in English about mental health services. Being a bilingual, he answered in French and that was his faux pas!
The Office of the Commissioner of Official Languages received 11 complaints because of that particular mishap alone, and an investigation was started. The total number of complaints eventually rose to 14.
While this may be a situation unique to Canada, it is an etiquette rule of thumb that in bilingual meetings (if the speaker who is asked a question is bilingual and so is the audience and no interpretation is provided) it is customary to answer in the language the question was asked in.
If some people in the audience understand only one language, it would be polite to answer in the language of the question and provide a small recap of your answer in the other language at the end.
If you deal with the audience that consists of monolinguals who speak different languages and if interpretation is provided, it is only fair to stick to your native language. Your expression in your native language will always be better, more subtle and nuanced.
It is also a diplomatic and protocol issue. In the United Nations there are 6 official languages: Arabic, Chinese, English, French, Russian, and Spanish.
While most representatives are bilingual, they would still choose to speak in their native language.
Imagine a hypothetical case, when a French diplomat chooses to speak in English and not in French about matters related to France at a meeting that has simultaneous interpretation between English and French. That is strictly speaking possible but may raise a few eyebrows.
It is disrespecting the language of your own country and the country itself by choosing to speak in a foreign language.
It is disrespecting and not recognizing the simultaneous interpreters who are working hard to get the message across accurately and professionally.
These are subtle etiquette points but – as we see from the Canadian example -they do matter. Yet another way to create rapport with your audience!