Monsanto is facing its first federal trial over allegations that its Roundup weedkiller causes cancer, but a US judge has blocked attorneys from discussing the corporation’s alleged manipulation of science. In an extraordinary move in a packed San Francisco courtroom on Monday, US judge Vince Chhabria threatened to sanction and “shut down” a cancer patient’s attorney for violating his ban on talking about Monsanto’s influence on government regulators and cancer research.“You’ve completely disregarded the limitations that were set upon you,” the visibly angry judge said to attorney Aimee Wagstaff, threatening to prevent her from continuing. “If you cross the line one more time … your opening statement will be over … If I see a single inappropriate thing on those slides, I’m shutting you down.”The unusual conflict in the federal courtroom has fueled concerns among Monsanto’s critics that the trial may be unfairly stacked against the plaintiff, Edwin Hardeman, a 70-year-old Santa Rosa man who alleges that his exposure to Roundup over several decades caused his cancer. Building on longstanding allegations, Hardeman’s lawyers and other critics have arguedthat Monsanto has for years suppressed negative studies and worked to promote and “ghostwrite” favorable studies about its herbicide to influence the public and regulators.