Members of Congress are rightly asking questions about a federal operation that was supposed to nab leaders of Mexican drug cartels but wound up costing scores of innocent lives - including the life of a federal agent.

The operation, called Fast and Furious, lasted 14 months. The Bureau of Alcohol, Tobacco, Firearms and Explosives allowed people whom it had under surveillance, and whom it believed to be delivering guns to Mexican drug cartels, to purchase more than 1,700 high-powered rifles and other weapons from gun dealers in Arizona. The buyers were allowed to "walk" with the guns, whose serial numbers were tracked, and to deliver them to drug runners. But once the guns were turned over to the third parties, agents were ordered to halt their surveillance.

The goal of the sting was to get the "higher-ups" in drug-running operations. But multiple federal agents fiercely objected to knowingly allowing the guns to be delivered to killers in drug cartels. Unfortunately, their objections were overruled or ignored - with tragic results.

Nearly 400 of the guns that were allowed to flow to the cartels later turned up at crime scenes in Arizona and Texas, and more than 150 Mexicans were killed or injured with the smuggled weapons. In addition, Agent Brian Terry was gunned down in an attack along the U.S.-Mexican border. To the horror of investigators, guns that the federal sting had allowed to be funneled to Mexican drug cartels turned up at the scene of the murder.

Now, the head of the ATF is expected to step down in the wake of a federal investigation of the botched sting. But the damage has already been done.

Protecting the U.S. border and fighting illegal drugs are difficult tasks in the best of circumstances. But it seems at least in this case that good judgment was suspended, and horrible results followed.