The retirement of Supreme Court Justice Anthony Kennedy announced on Wednesday could have dramatic and detrimental effects on environmental quality.

Since the retirement of Justice Sandra Day O'Connor in 2006, Kennedy has been a pivotal vote on the court, siding with the majority on at least two crucial rulings to expand the reach of the EPA.

The most critical, from the standpoint of those interested in cleaner transportation, was his ruling in "Massachusetts v. the Environmental Protection Agency," which ordered the EPA to determine whether carbon-dioxide constitutes a pollutant. That led to the EPA's "endangerment finding," which made the legal determination that CO2 is a harmful greenhouse gas.

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That led in turn to the EPA under the Obama Administration coordinating with NHTSA, which has statutory authority over fuel economy, to tighten emissions and raise fuel economy standards for cars for the first time since 1992.

It also led the EPA to create the Clean Power Plan to clean up emissions from powerplants by requiring coal-powered stations to implement carbon-capture technology or convert to cleaner fuels.

Along with market forces driving down prices for solar and wind power and clean-burning natural gas, the Clean Power Plan has been a key driver of less polluting electrical grids in most parts of the U.S.

EPA administrator Scott Pruitt [photo from 2014]

EPA administrator Scott Pruitt [photo from 2014]

The saying that the dirtiest an electric car will ever be is the day you buy it, promoted by electric car advocates especially at the Union of Concerned Scientists, is partly dependent on the Clean Power Plan.

Under Administrator Scott Pruitt, the EPA has said it will rescind the Clean Power Plan, limit increases in emissions and fuel economy standards, and work to repeal California's right to set stricter standards.

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The second major environmental ruling in which Kennedy was the decisive swing vote expanded the scope of the Clean Water Act to protect more rivers, streams, and wetlands.

Stricter environmental protections for these bodies of water have led to more prosecutions for dumping or spilling coal ash, oil, and other residues of fossil-fuel consumption into waterways.

Under Pruitt, the EPA has reduced the number of criminal investigators at the Agency, and announced that it would repeal the rule designed to meet Kennedy's expansion of the definition of waterways protected under the Clean Water Act.

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