The general rule is that a person cannot be compelled to provide evidence that would subject him to criminal or civil liability either under Australian or foreign law. This is called privilege against self-incrimination. Sec 128 of the Evidence Act 1995 provides the exception.
According to this law a person may be required by the court to testify or provide evidence if it is satisfied that:
Whether the person willingly or unwillingly gives such evidence, the court will issue a certificate which prevents the future use of the evidence against the person. The court will also issue such certificate if it later determines that there were reasonable grounds for objecting to the production of the evidence.
This certificate serves as protection for the person who provided the evidence. Therefore the person can use the certificate against any proceeding before a New South Wales court, person or body authorized by the State or by consent of the parties to receive and examine evidence.
There are some instances, however, when the certificate has no use. It cannot be used in a criminal proceeding when the issue is the genuineness or falsity of the evidence provided. It also cannot be used in a retrial of the same defendant or a trial for arising for an offence arising from the same facts.
A body corporate does not enjoy the privilege against self-incrimination, not being a person but a juridical entity.