In a market where a dolphinsafe label is a competitive necessity, access to that label effectively determines access to the American consumer market for tuna.
The U.S labeling law prohibits any tuna caught using this method in this part of the ocean from being labeled dolphinsafe even if an observer certifies that no dolphins were killed.
Without this law, consumers would be free to demand tuna caught without setting on dolphins, or they might prefer to buy only tuna whose capture was certified as dolphinsafe by an independent observer.
What makes the law discriminatory and misleading is that tuna caught elsewhere, like the Western Central Pacific where U.S. fishing fleets operate, may be labeled dolphinsafe without any certification that dolphins were not harmed.
The federal requirements for dolphin-safe labeling do not exclude tuna that were caught while killing dolphins as long as it was not done using one particular method in one particular part of the ocean.