Each witness will re-enter alone, when he or she is called to testify. You may also take an oath in a form that is recognized by your religion. If you choose to do this, please inform the defence lawyer or Crown attorney before your appearance date. In all cases, the clerk will ask you if you promise to tell the truth, and you should answer 'I do'. After you have given testimony, you may stay for the remainder of the trial if you wish, unless the judge tells you otherwise.
Perjury is a criminal offence, and it occurs when a witness tells a lie.
It carries a jail term of up to 14 years. Contact your local police immediately. If this happens at the court house while you are waiting to testify, report it immediately to a police officer. The Charter of Rights protects you from self incrimination - that is, giving testimony that may be used against you in another court case. If you have a question about this matter, it's best to consult your own lawyer or the lawyer who contacted you to appear in court.