Elsewhere in Minnesota, a trial began Monday for three activists who face felony charges for their civil disobedience action in 2016, when they manually turned off a pair of Enbridge tar sands pipelines. The so-called valve turners—Annette Klapstein and Emily Nesbitt Johnston, along with a support person, Benjamin Joldersma—are mounting a “necessity defense,” saying their civil disobedience was justified by the urgent need to stop climate change. But on Monday, a Minnesota district court judge ruled that expert witnesses, including 350.org founder Bill McKibben and former top NASA climate scientist James Hansen, will not be allowed to testify on their behalf.