Does Monsanto’s Roundup cause cancer? The law says yes, the science says maybe
A federal jury in California has unanimously decided that the weedkiller Roundup was a “substantial factor” in causing the lymphoma of 70-year-old Edwin Hardeman, who had used Roundup on his property for many years, and awarded Hardeman US$80 million in damages. This is the second such verdict in less than eight months. In August 2018 another jury concluded that groundskeeper DeWayne Johnson developed cancer due to his exposure to Roundup, and ordered Monsanto, the manufacturer, to pay Johnson nearly US$300 million in damages.
In product liability cases like these, plaintiffs must prove that the product was the “specific cause” of the harm done. The law sets a very high bar, which may be unrealistic for harms such as a diagnosis of cancer. Nonetheless, two juries have now ruled against Roundup.
Monsanto’s lawyers insist that Roundup is safe and that the plaintiffs’ arguments in both cases were scientifically flawed. But jurors believed that they were shown enough evidence to meet the legal criteria for finding Roundup was the “specific cause” of cancer in both men.
As a result of these high-profile trials, Los Angeles County has halted use of Roundup by all of its departments until clearer evidence is available about its potential health and environmental effects.
Although “proof” has a similar primary meaning in science and law – a consensus of experts – how it is achieved is often quite different. Most importantly, in science there is no deadline for a discovery, whereas in law, timeliness is paramount. The conundrum is that a legal decision may be required for a potentially dangerous product on the market before the science has been settled.
What is ‘proof’?
Proof is an elusive concept. Do we need proof that our glimpse of stripes in the jungle is a tiger before we run? Do we need proof that the jet engines are reliable before clearing a plane to take off for London with 300 passengers on board?
Can proof ever be absolute, or is it inherently a statement of probabilities?
Scientists use proof to advance our understanding of nature. Science assumes that there is an objective reality underlying all of nature, which we can eventually understand. Nature has no moral compass: It is neither good nor bad – it simply is. Scientists are human, so they experience joy or disappointment depending on the outcome of an experiment, but those emotions do not alter the truths of nature.
In contrast, lawyers use proof to find justice for people. Law is built on the premise that there are widely accepted codes of human behavior, which should be rectified when they are violated. Ideally, justice under the law is a highly moral endeavor with fairness at its core.