VICTORIA, B.C. — It could have been an unprecedented law-enforcement victory: Last year's seizure by U.S. agents of more than 2½ tons of pure cocaine aboard a Canadian fishing boat off Washington's Cape Alava was the biggest drug bust ever in the Pacific Northwest. But more than 16 months later, no one has been arrested or charged with a crime in the United States or Canada. The boat's captain — caught carrying more cocaine than is usually seized in all of Canada in a year — is protected from prosecution by the very system he betrayed. And Canadian drug investigators...