On Wednesday, settling a dispute between environmentalists and the United States Navy, the Supreme Court ruled that the latter could use sonar for their training exercises off the California coast, thus dismissing the environmental groups’ claims that the sonar might harm whales.

Previously, environmental activists had convinced several federal courts in California to regulate the use of sonar in exercises aimed at detecting enemy submarines, by instating some restrictions in order to protect marine mammals.

Nevertheless, the Supreme Court failed to focus on the arguments presented by the environmentalists, who in a hearing that took place back in October, stated that the mid-frequency sonar could even come to kill the whales. The marine mammals’ death could occur by virtue of the fact that whales, in their attempt to steer clear of the sound the sonar made, would dive deeper into the water and thus suffer from decompression sickness (triggered by the sudden decrease, following a major increase, in the pressure around their body).

In making their decision, Supreme Court Justices factored in almost exclusively the need for proper and realistic training where submarine-hunting was concerned, which is deemed by the U.S. military force as vital to the nation’s security. Moreover, they considered the rulings made by the federal courts to have been an abuse of their lower than the Supreme Court’s power.

A federal court in San Francisco ruled in February that the Navy must adhere to rules on the powerful sonar for tracking submarines, including establishing a buffer zone within 20 kilometres of the California shore, and shutting the system down if marine mammals are spotted within 2,000 metres of the ships.

The majority opinion was written by Chief Justice John Roberts, whose views on the matter were shared by Justices Samuel Alito, Anthony Kennedy, Antonin Scalia and Clarence Thomas.

"We do not discount the importance of plaintiffs ecological, scientific, and recreational interests in marine mammals," Chief Justice John Roberts said in writing the majority's opinion.

"Those interests, however, are plainly outweighed by the Navys need to conduct realistic training exercises to ensure that it is able to neutralize the threat posed by enemy submarines," Roberts said.

The Navy says it has instituted 29 measures to protect sea life, including lookout stations, passive acoustic monitoring for marine mammals and the setting up of safety zones to reduce the sonar power or shut it down if marine life is spotted.