As Grist readers know, today a federal judge struck down the EPA's controversial mercury cap-and-trade system.

The decision (PDF) is just the latest in a series of successful court challenges to pro-industry Bush environmental rules.

This did not come as a shock. It has been commonly assumed in D.C. that the Bush administration's attempt to pretend that mercury is not toxic when it comes out of a power plant smokestack would be judged illegal.

Despite this decision, however, mercury cleanup will continue to languish, because the Bush crowd will continue foot dragging. Their gambit bought the industry an extra five years, at least.

The decision is a strong argument for Congress to step in and pass the power plant legislation introduced by Senator Tom Carper of Delaware.