Federal Court Justice Michael Lee will on Thursday hand down a judgment in the class action against popular herbicide Roundup.
The case, launched by Maurice Blackburn Lawyers, claims Roundup's active ingredient glyphosate caused the cancer of more than 800 Australian non-Hodgkin lymphoma patients.
It's alleged glyphosate is a carcinogen to humans and exposure to the ingredient increases the risk of developing cancer.
The case was launched in the Federal Court against Monsanto, which produced Roundup. Bayer acquired Monsanto in 2018.
Bayer has previously stated glyphosate-based herbicides have been rigorously tested in hundreds of studies and the science confirms glyphosate is safe when used as directed.
Justice Lee will on Thursday rule whether glyphosate is carcinogenic and capable of causing non-Hodgkin's lymphoma in humans.
The court is yet to consider lead applicant Kelvin McNickle's individual claim Roundup caused his cancer.
The 40-year-old Queensland man allegedly used the herbicide as a child while spraying weeds with his father and at work as an adult before being diagnosed with non-Hodgkin lymphoma in 2018.
Mr McNickle's claim, and the claims of the other group members, will be determined after Thursday's judgment and following any possible appeals from Bayer or Maurice Blackburn.
The class action lawyers previously flagged their clients were seeking significant damages.
Roundup is still used in Australia and the Australian Pesticides and Veterinary Medicines Authority supports the company's claim glyphosate-based herbicides are not carcinogenic.