Plaintiff Edwin Hardeman was initially awarded $75 million in punitive damages and around $5 million in compensatory damages by a jury in March, but US District Court Judge Vince Chhabria has reduced the punitive damages to $20 million.

The judge highlighted legal precedent establishing that punitive damages should not be more than four times bigger than compensatory damages, Bloomberg reports.

Mr Hardeman is one of 13,400 consumers suing pharmaceutical giant Bayer, which acquired Monsanto for $63 billion last year, over the herbicide’s cancer links.

Bayer has already lost three court cases over Roundup and analysts believe it will now have to pay out at least billions of dollars in settlements.

In May, a jury in California awarded over $2 billion to a couple who claimed the Roundup weed killer had caused their cancer, though the award would be reduced to $275 million if Judge Chhabria’s rule is applied.

Attorney Jennifer Moore, representing Mr Hardeman, said the judge’s decision to uphold the verdict was a “major victory” for consumers, but criticised the decision to reduce the damages award.