Appeals Court Judge Sonia Sotomayor is now President Obama's official nominee for the Supreme Court, and her background has already been picked apart by liberals and conservatives alike. But what does Sotomayor's appointment mean in terms of the environment?

The Wall Street Journal reports that Sotomayor has an important environmental ruling under her belt — one that was just overturned by the Supreme Court, but may provide some insight into her environmental views.

In the case of Riverkeeper vs. EPA in 2007, Sotomayor argued that the Environmental Protection Agency can't weigh costs and benefits in determining the "best technology" for protecting fish that are threatened by power plants because Congress has already decided that marginal costs of extra environmental protections are worth it.

That case was a challenge to an EPA rule regulating cooling-water intake structures at power plants and their impact on aquatic life. Sotomayor found that,

"…assuming the EPA has determined that power plants governed by the Phase II Rule can reasonably bear the price of technology that saves between 100 - 105 fish, the EPA, given a choice between a technology that costs $100 to save 99 - 101 fish and one that costs $150 to save 100 - 103 fish (with all other considerations, like energy production or efficiency, being equal), could appropriately choose the cheaper technology on cost-effectiveness grounds.

The Agency is therefore precluded from undertaking such cost-benefit analysis because the [best technology available] standard represents Congress’s conclusion that the costs imposed on industry in adopting the best cooling water intake structure technology available (i.e., the best-performing technology that can be reasonably borne by the industry) are worth the benefits in reducing adverse environmental impacts."

Patricia Millett, co-leader of Akin Gump Strauss Hauer & Feld's Supreme Court and appellate practice, believes that Sotomayor's decision in Riverkeeper vs. EPA does not necessarily indicate a hard-line stance on the environment.

"She was taking the statute at its word, so I don't think you can really read much into it," Millett says.

Supreme Court Justice nominee Sotomayor has environmental record
Nominee Sonia Sotomayor sided with the fish against power companies in a 2007 case.