You should also care about the Supreme Court.

In a setback for environmentalists, the Supreme Court ruled on Wednesday that federal regulators may consider costs when deciding whether to order the operators of power plants to install protections for fish.

By 6 to 3, the court overturned a ruling by the United States Court of Appeals for the Second Circuit, in Manhattan, which had ruled that the Clean Water Act barred the Environmental Protection Agency from engaging in the kind of cost-benefit analysis that it had proposed.

The recent narrow-but-good decision in Massachusetts v. EPA shouldn’t fool anyone into thinking that the Supreme Court is a particularly green institution at the moment, and today’s 6-3 decision (Justice Breyer wrote a concurrence) should be a reminder that the “liberal” wing of the Court is far from uniform. There’s a big difference between a good Justice and a great one, especially when it comes to environmental issues.