Save the Whales, or the U.S. Navy Sonar?

Environmentalists fear that if the Navy wins in this case, it could set a dangerous precedent.

"If they accept the Navy's premise that the president and the Navy are entitled to a blank check in how they use sonar, then that would be a dangerous precedent and it would be a significant departure from what the law has been in this country for hundreds of years," NRDC senior attorney Joel Reynolds said.

"Our Constitution is grounded on the fact that all of us have to comply with the law. Nobody is above the law, and that includes the U.S. Navy," he said.