Privileged documents and communications
Many communications between you and your Australian patent attorney have a privileged status. This has been confirmed in a recent decision of the Federal Court of Australia, Australian Mud Company v Coretell Pty Ltd,  FCA 200 (the “Mud” decision).
You can assert that the privileged communications are not admissible as evidence to a court. For example, if a party seeks to revoke your patent, then they can be prevented from using privileged communications to support their revocation claim.
While there are times that discretion is desirable, generally you can communicate with your patent attorney freely so that your attorney has the information needed to give the best advice. Especially sensitive communications, for example in relation to patent infringement and validity, may be communicated verbally rather than in writing.
The Patents Act (1900) was recently amended to strengthen the privilege. Now, the privilege attached to communications between a client and a patent attorney has the same extent of protection as such communications would be protected if they were between a legal practitioner and their client.
It is important to note that the privilege only extends to communications and documents made for the dominant purpose of a registered Australian patent attorney providing intellectual property advice. The privilege does not extend beyond intellectual property matters.
The Mud Judge (Nicholas J) made some interesting statements in relation to privilege and the preparation of patent applications. The Australian Mud Company was attempting to enforce its patent against Coretell Pty Ltd. Coretell cross claimed that the patent was invalid and should be revoked. In support of the cross claim, Coretell Pty Ltd wished to admit as evidence emails between the patent applicant and an external consultant. The emails included schematics and drawings in relation to the invention, and requested assistance from the external consultant to prepare materials to enable the patent attorney to prepare a patent application.
Nicholas J inferred that the communications and documents were produced for obtaining the patent attorney’s professional advice or assistance and thus had privileged status. Nicholas J followed Pratt Holdings Pty Ltd v Commissioner of Taxation  FCAFC 122, which is authority for the proposition that privilege may be attracted where a client has authorised a third party to bring a document into existence for the dominant purpose of communicating the document or its contents to his or her legal advisors in order to obtain legal advice, even though the third party who prepared the document might not have done so as an agent of the client.
Neither did, in the opinion of Nicholas J, subsequent publication of the patent application or public use of the invention result in the loss of privilege.
Finally, it is important to note that a privileged communication or document is in danger of losing its privileged status if you knowingly and voluntarily disclose the substance of the communication or document, or it is disclosed by another with your consent.