The Supreme Court appeared split Monday over whether to allow lawsuits against Bayer for not including a warning label about cancer risks on its Roundup weedkiller to proceed, as the company and the Justice Department argued that federal law preempts state labeling laws for herbicides and pesticides.

The justices heard arguments in Monsanto v. Durnell over whether the Federal Insecticide, Fungicide, and Rodenticide Act preempts a “failure-to-warn” about labels if the Environmental Protection Agency did not require a warning. A “failure-to-warn” is when a company fails to disclose that a product poses some type of significant hidden danger, such as by containing chemicals linked to cancer, in violation of the law.