Etiquette firmly opposes both obscene and malicious talk, but this does not imply that speech needs to be restricted by law  Etiquette does not necessarily even oppose the expression of offensive ideas
Rather, it dictates that there are situations in which the expression of potentially offensive, disturbing, or controversial ideas is inappropriate and that, where appropriate, the expression and discussion of such ideas is to be done in a civil manner
When prosecutors elicit testimony from a cooperative witness they should do so without intensive questioning.