The Supreme Court unanimously said Tuesday that federal decisions on whether a piece of land is a wetland under the Clean Water Act can be challenged in court.

All eight judges on the nation's highest court voted in favor of upholding judicial review of U.S. Army Corps of Engineers decisions in the case Army Corps of Engineers v. Hawkes.

In the opinion, Chief Justice John Roberts wrote that the Administrative Procedure Act allows three peat-mining companies to ask a court to immediately review a Corps decision to not allow them to mine a piece of land in northern Minnesota that the Corps determined was a wetland. Three other justices wrote concurring opinions.

The decision could have a major impact, given that Army Corps rulings on what constitutes a wetland cover a huge amount of land. Roberts wrote that the Corps has determined there are 270 million-300 million acres of wetlands in the United States, including half of Alaska.

The mining companies wanted to discharge fill material into federally protected waters as a part of their mining activities. However, the Corps indicated the permitting process would cost the companies more than $100,000, Roberts wrote.

The goverment's argument, that the companies couldn't challenge the Army Corps decision ruling until they had mined and faced charges under the Clean Water Act or that they could go through the complex and expensive permitting process, didn't hold water, Roberts wrote.

He said landowners shouldn't have to wait until the end of the permitting process, which "can be arduous, expensive and long."

The Corps determined the area the companies were looking to mine were connected to the Red River of the North, which is about 120 miles away. The companies sued, saying that the area was not connected to any navigable water. A district court found that the companies had no standing to challenge the decision, but the 8th Circuit Court of Appeals disagreed.

"The Corps contends that the revised [decision] is not 'final agency action' and that, even if it were, there are adequate alternatives for challenging it in court. We disagree at both turns," Roberts wrote.