Bayer AG shares soared in Frankfurt on Thursday morning after the Supreme Court sided with the German pharmaceutical and life sciences giant in a major Roundup ruling expected to block thousands of lawsuits alleging it failed to warn consumers that the weedkiller could cause cancer.

Bloomberg reported that the Supreme Court voted 7 - 2 to throw out a $1.25 million jury verdict won by Missouri resident John Durnell, who blamed years of Roundup exposure for his non-Hodgkin's lymphoma.

Justice Brett Kavanaugh wrote for the majority that federal law "demands" uniform pesticide labels and that the state-law "failure-to-warn" claim at issue in the case "would require a cancer warning on Roundup's label, a requirement 'in addition to' and 'different from' the label required by EPA."

Justices Ketanji Brown Jackson and Neil Gorsuch dissented.

The ruling is a major milestone in Bayer's years-long court battle over Roundup, which it acquired from Monsanto for $63 billion in 2018. The company has since stopped using glyphosate in Roundup products sold at major retailers.

Earlier this year, Bayer announced a proposed $7.25 billion class action settlement to resolve tens of thousands of current and future lawsuits.

Shares of Bayer soared 20%...

...marking the largest intraday gain since March 2003.

Bloomberg Intelligence analyst Holly Froum wrote in a note before the high court ruling that about $787 million in existing Roundup verdicts could be affected by the decision.

To sum up, the high court ruled that consumers cannot sue Bayer over the absence of a cancer warning on Roundup labels because federal regulators had already concluded that such a warning was not required.