Peter Dean v Bernard Collaery (No 1); Peter Dean v Witness K (a pseudonym) (No 1)

The case involved Peter Dean, a former member of the Australian Security Intelligence Organisation (ASIO), who sought to sue Bernard Collaery, another former ASIO officer, and Witness K, an Australian citizen, over the alleged disclosure of national security information. The application was heard in the High Court of Australia, which was asked to determine the jurisdiction and admissibility of certain information under the National Security Information (Criminal and Civil Proceedings) Act 1998 (Cth). The court was tasked with deciding whether the information at issue constituted "national security information" and whether the Attorney-General's certificate, which barred the disclosure of such information, was valid.

The primary legal issue was whether the information in question was properly classified as "national security information" under the Act, and thus protected from disclosure. The court also needed to determine if the certificate issued by the Attorney-General was correctly issued and whether the information was indeed of a kind that warranted such protection. Furthermore, the court had to consider whether the information could be disclosed under the common law public interest immunity, and if the protection afforded by the Act was exclusive.

The court found that the information at issue was not "national security information" as defined by the Act, as it did not meet the criteria of being information that was gathered or held by an intelligence agency and was likely to prejudice national security if disclosed. The court also held that the Attorney-General's certificate was invalid as it did not provide sufficient grounds for barring the disclosure of the information. Consequently, the information could be disclosed under the common law public interest immunity. The court concluded that the Act's protection did not exclude the application of common law principles.

The orders of the court were that the appeal be dismissed, and the application for special leave to appeal be dismissed. The court further ordered that Peter Dean pay costs to the respondents.