The night before Donald Trump's inauguration, five environmental lawyers filed a federal court brief defending an Obama administration clean-water rule that the new president and his Republican allies have targeted for elimination, considering it burdensome to landowners. The move served as a warning that environmentalists, facing a hostile administration and a Republican-dominated Congress, are prepared to battle in court against what they fear will be a wave of "It's going to be all-out war," said Vermont Law School Professor Patrick Parenteau.