The United States has done more than any other country to protect whales, porpoises, seals and other marine mammals. In 1973, for example, Congress enacted the Marine Mammal Protection Act, a comprehensive law prohibiting hunting, killing, or even harassing them.

On Nov. 12, the U.S. Supreme Court balanced protecting marine mammals with the Navy's use of sonar to detect silent diesel-electric submarines. In Winter v. Natural Resources Defense Council, the court voided strict rules imposed on sonar training in Southern California waters, declaring judges should hesitate before second-guessing the Navy's judgment.

Environmentalists claimed mid-frequency active (MFA) sonar frightens or injures whales. The lower courts enjoined sonar use within 12 miles of California's coastline, or if whales were spotted within 1.2 miles of any ship.

The courts rejected the assertion these limitations interfered with the Navy's use of MFA sonar to detect submarines designed to avoid discovery by other types of sonar.

The Navy employs two types of sonar: passive sonar listens for sounds emitted by submarines; active sonar transmits sound and listens for a reflection. Active sonar is the most effective means to detect diesel-electric submarines that are deployed by China, North Korea, and Iran, and are specifically designed for silent running. A single torpedo can sink an aircraft carrier with a crew of 4,000. These submarines can also carry nuclear, biological or chemical weapons.

Nine retired admirals with more than 300 years of service among them and a coalition of support organizations including the Navy League filed a Supreme Court brief emphasizing the threat from silent submarines, and that sailors should not be precluded from training realistically. No one questioned the need to train, but under the lower courts' restrictions, the first time a sonar operator could fully deploy sonar equipment is when it counted and there was no margin for error.

Some blame active sonar for whale beachings and injuries, although there has not been any documented case of harming a marine mammal in the 40-plus years sonar has been used in the Southern California training area. These animals inhabit the world's oceans, and Congress understood the desire to protect them may conflict with national defense.

In 2004, it amended the MMPA allowing the secretary of defense to exempt actions of the Department of Defense if necessary. This exemption was enacted following an earlier California case in which environmentalists challenged the Navy's use of low-frequency active sonar. The exemption allows sonar training even if it might, in some circumstances, injure marine mammals.

Even with this exemption, the Navy takes extraordinary measures to minimize any effects MFA sonar may have. Fleet-wide measures include extra lookouts with enhanced search procedures, limitations on transmission levels within 1,000 yards of mammals and additional powering down of sonar when mammals are inside 500 yards from sonar equipment.

But these measures were not enough for the lower courts, which rejected the judgment of military commanders and the legislative and executive branches that sonar would not likely cause harm, and even if it did, the need to prepare the Navy was, on balance, more important. In effect, the courts substituted their judgment for that of experienced professionals in how to best train to hunt sophisticated enemy submarines.

The Supreme Court recognized that judges haven't the expertise to evaluate threats, and the injunction unnecessarily put sailors, and the nation they defend, at risk. The court noted, "neither the members of this court nor most federal judges begin the day with briefings that may describe new and serious threats to our nation and its people." The need to train sonar operators for deployment is of paramount public interest; it is not worth jeopardizing the fleet with inadequate training just to allay environmental groups' fears that their desire to "take whale watching trips, observe marine mammals underwater, conduct scientific research on marine mammals, and photograph these animals in their natural habitats," might be harmed.

The court is right. The Navy and its leaders — not judges — should determine how best to defend our nation from silent-running submarines.

Robert H. Thomas and Mark M. Murakami are Honolulu attorneys who filed a brief in the Winter v. NRDC case on behalf of nine retired Navy admirals, the Navy League of the United States-Honolulu Council and a coalition of military service organizations. They wrote this commentary for The Advertiser.