US court rules in favour of Navy over whales

Chief Justice John Roberts wrote the majority opinion, which was joined by Justices Samuel Alito, Anthony Kennedy, Antonin Scalia and Clarence Thomas.

The court did not deal with the merits of the claims put forward by the environmental groups. It said, rather, that federal courts abused their discretion by ordering the Navy to limit sonar use in some cases and to turn it off altogether in others.

The overall public interest tips "strongly in favor of the Navy," Roberts wrote. He said the most serious possible injury would be harm to an unknown number of the marine mammals.

"In contrast, forcing the Navy to deploy an inadequately trained anti-submarine force jeopardizes the safety of the fleet," the chief justice wrote.

In dissent, Justice Ruth Bader Ginsburg said that the Navy's own assessment predicted substantial and irreparable harm to marine mammals from the service's exercises. She said that "this likely harm ... cannot be lightly dismissed, even in the face of an alleged risk to the effectiveness of the Navy's 14 training exercises."