The hiring of ill-behaved misfits became so serious that airlines, foreign police, and American embassies started to complain.

Since 9/11, more than three dozen federal air marshals have been charged with crimes, and hundreds more have been accused of misconduct, an investigation by ProPublica, a non-profit journalism organization, has found. Cases range from drunken driving and domestic violence to aiding a human-trafficking ring and trying to smuggle explosives from Afghanistan. ...

Since 9/11, air marshals have taken bribes, committed bank fraud, hired an escort while on layover and doctored hotel receipts to pad expenses, records show. They've been found sleeping on planes and lost the travel documents of U.S. diplomats while on a whiskey-tasting trip in Scotland.

The Air Marshal Service says it has the highest firearms qualification standard among federal law enforcement agencies. Yet police and court records show some marshals have used their weapons imprudently:

In 2003, a New York air marshal pulled his gun in a dispute over a parking space. Another failed to turn over his ammunition on an international trip, as required by diplomatic agreements, and was detained by Israeli airport security in 2004. That same year, a Las Vegas air marshal "discharged" his gun in a hotel room, penetrating a wall and shattering a mirror. In April, a Phoenix air marshal fired his during a fight outside a bar.

Still another left his handgun in the plane's lavatory in 2001, according to court papers. He realized it was missing only after a teenager found it.

The director of the Air Marshal Service argues that "the misconduct cases don't represent the exemplary work done by the vast majority of air marshals." Perhaps a large law enforcement agency can't be expected to screen out every potential criminal, drunk, and incompetent during the hiring process. The question is why so many made it into the supposedly elite force of air marshals.