Answer ... There is an onus on the party bringing the action to demonstrate that the patent is invalid.
The standard used by the courts and by the Australian Patent Office is the ‘balance of probability’ test. This requires the person making the decision - whether an examiner of first instance or a judge at the appeal stage - to weigh up the allowable evidence and decide, in the case of conflicting evidence, what the most probable finding of fact should be.
The rules of evidence are not strictly applied in proceedings before the Australian Patent Office, which is considered to be a tribunal and not a court. In patent hearings, the person making the decision will generally weigh up all the evidence presented. There is broad discretion as to how much weight the decision maker will give to any part of the evidence. For example, hearsay evidence is permissible in Australian Patent Office proceedings, although the decision maker will consider how reliable and probative it is and will give it appropriate weight. Hearing officers in the Australian Patent Office are usually highly technically skilled, but have only limited legal training, so the emphasis is to arrive at a correct outcome where both parties are given natural justice.
Previously, the Australian Patent Office used an evidentiary standard where the patent applicant received the benefit of the doubt. A patent application would proceed to grant unless it was practically certain that the subsequently granted patent would be invalid.
The rules of evidence are applied more strictly in court proceedings. Formal challenges to the admissibility of evidence may be made.
In the case of alleged infringement of a patented process for preparing a product, the onus reverses to the alleged infringer if the product is identical to the product obtained by the patented process. In that case, in the absence of proof to the contrary, the defendant’s product will be taken to have been obtained by the patented process.
Expert evidence is generally put on in opposition and court proceedings, and may in some cases also be used in ex parte proceedings in the Australian Patent Office, such as re-examination. Expert evidence is generally confined to matters of technical fact and the state of the common general knowledge. Evidence from the parties may also need to be weighed in cases where inventorship is in dispute.
In proceedings before the Australian Patent Office, evidence is almost invariably presented in the form of a signed declaration. In patent opposition proceedings, the opponent presents its evidence in support, which is then responded to by the applicant’s evidence in answer. The evidence in these rounds is broad ranging and the parties are free to address any issue they see fit. There is a further round of evidence in reply from the opponent. Evidence not strictly in reply may be given reduced weight. In general, the Australian Patent Office is unsympathetic to requests to file additional rounds of evidence or to allow additional time, even in cases where the parties might be in agreement.
In court proceedings, the plaintiff first provides its evidence in chief, which is then responded to by the defendant. The courts generally adopt a more flexible approach and will in most cases consent to an evidentiary schedule agreed by the parties. This is often necessary as the court will usually be dealing with invalidity as part of a counterclaim to infringement.
Witness statements are almost never tested by cross-examination in Patent Office proceedings, but they are in court proceedings. Expert witnesses for the parties are often required by the court to consult and prepare a joint report in which they set out points of agreement and points of difference. The witnesses may then be required to provide conjoint evidence, where they are examined and cross-examined together on the relevant issues.