The environmental movement was dealt a de facto blow yesterday when the U.S. Supreme Court declined to consider a case involving the practice of mountaintop removal mining in West Virginia. As its name suggests, the practice involves leveling hilltops with explosives to expose underlying coal seams. The remains of the mountain — tons of dirt and rock — are subsequently dumped into nearby valleys, where they clog rivers and streams. The West Virginia Highlands Conservancy and local landowners sued the state’s top environmental agency for issuing mountaintop-removal mining permits. A federal judge sided with the conservancy, but last year, an appeals court ruled that such disputes belong in state courts instead. By declining to hear the case, the Supreme Court let that decision stand, a move that some fear will make it harder for citizens to sue on environmental issues.