The Trump administration gave its final rewrite of a rule on how agencies conduct environmental reviews a better chance of surviving legal challenges by backing away from clear language that may have been vulnerable to attack, but in doing so, it may have created new problems by leaving certain terms up to agencies to define. The White House on Wednesday stepped back from the proposed rule’s total ban on consideration of a project’s “indirect” effects on the environment during a National Environmental Policy Act review, while declining to completely spell out what types of projects are exempt from NEPA reviews. By avoiding hard-line positions that environmental groups and more liberal states could have challenged as arbitrary or capricious, the White House Council on Environmental Quality gave more protection to its final rule from one line of attack. Yet the choice to be less clear leaves blanks for federal agencies to fill — and that opens a Pandora’s box of potential litigation, experts say. “So much is going to depend on the way that this is implemented,” Caitlin McCoy, a staff attorney with the Environmental & Energy Law Program at Harvard Law School, said. “By opening up a lot of different elements of these regulations to interpretation in order to avoid taking hard positions that could be challenged as arbitrary, CEQ is just exposing all of the agencies to a huge round of litigation.” …That means while the rule might be more legally sound and helps fulfill the goal of narrowing the types of projects that require NEPA reviews — creating more certainty for project proponents and speeding up the process — there still will be lots of chances for opponents to thwart those aims at the agency level, McCoy said.