Witnesses appearing before committees enjoy the same freedom of speech and protection from arrest and molestation as do Members of Parliament. At the committee’s discretion, witnesses may be allowed to testify in camera when dealing with confidential matters of state or sensitive commercial information. Tampering with a witness or in any way attempting to deter a witness from giving evidence at a committee meeting may constitute a breach of privilege.
Parliamentary Counsel (Legal) may assist witnesses during the questioning, although permission for such assistance is seldom sought. Counsel, when permitted, is restricted to an advisory role and may not ask questions or reply on behalf of the witness.
There are no specific rules governing the nature of questions that may be put to witnesses appearing before committees, beyond the general requirement of relevance to the issue before the committee. Witnesses must answer all questions that the committee puts to them. A witness may object to a question asked by an individual committee member. However, if the committee agrees that the question be put to the witness, he or she is obliged to reply.
Particular attention has been paid to the questioning of public servants. The obligation of a witness to answer all questions put by the committee must be balanced against the role that public servants play in providing confidential advice to their Ministers. The role of the public servant has traditionally been viewed in relation to implementing and administering government policy rather than determining what that policy should be. Consequently, public servants have been excused from commenting on the policy decisions made by the government.
As is the case with the House, committees respect the sub judice convention whereby Members refrain from making reference to certain matters, particularly criminal cases, that are before the courts. The convention is applied not only in the discussions held amongst members of the committee but also in the questioning of witnesses, including Ministers of the Crown.