An inventor is entitled to the grant of a patent. That is, unless there is some obligation, such as an agreement to assign rights or employment. But how can you tell whether more than one person should be considered an inventor?
This question arose in Polwood Pty Ltd v Foxworth Pty Ltd  FCAFC. In this case, the patent application described two aspects of the invention. The first was a method and a process for producing plant growth media. The second was an apparatus for producing the plant growth media.
In this case, Polwood appealed against a finding by the Federal Court that Foxworth (through obligated inventors) was the inventor of the apparatus. Foxworth did not pursue a finding that it was entitled to the method/process aspect. But Polwood maintained that because it was entitled to the "inventive concept", it was also entitled to the apparatus, to the exclusion of Foxworth. Polwood recognised that Foxworth first constructed the apparatus, but said that was no more than an implementation of the completed and final Polwood concept.
Their honours stated that the entitlement to the grant of a patent as the inventor is not determined by quantitative contribution. In other words, the role of joint inventors does not have to be equal. The issue is whether the contribution was to the invention. The invention can be determined from the particular patent specification, including the claims.
In JMVB Enterprises Pty Ltd v Camoflag Pty Ltd (2005) 67 IPR 68, Crennan J said that rights in an invention are determined by objectively assessing contributions to the invention rather than assessing the inventiveness of respective contributions. Her honour said that if the final concept of the invention would not have come about without a particular person's involvement, then that person has entitlement to the invention.
It appeared that the heart of the dispute in this matter was how the court should determine the invention. Their honours noted that the patent application described the apparatus as an aspect of the invention. The evidence revealed that Polwood played no part in the design and construction of the apparatus, which was found to be "an invention" of Foxworth. Foxworth had therefore contributed inventively. Thus, their honours were not satisfied that Polwood was solely entitled to the grant of the patent.
Before you can indentify the inventors, you need to define the invention. Once that's been done, the following question should be asked of all who contributed: "Would that invention have come about without x's contribution?" If the answer is no, x is an inventor. Clearly, defining the invention is the tricky part, as this case illustrates.
Because defining the invention is difficult, patent applicants should identify all people who contributed in some way. Then, to be safe, even if you think that contributors did not exercise any inventive faculties, have them sign a Deed of Assignment anyway.
Practitioners should be asking for details of everyone who was involved during the conception and reduction to practice of an invention and then making sure that they all signs Deeds of Assignment.