The Dallas Police Department fought quite a campaign in the war on drugs last year, seizing a fair share of cocaine, methamphetamine, and, of course, pulverized wallboard.

The Dallas Morning News broke the story in January, and it goes something like this: A paid informant had tipped off the cops on dozens of supposed drug dealers over the past two years. All of them were working-class Mexican immigrants who spoke limited English. A search in each case turned up large quantities of a white substance that the arresting officers said tested positive in the field for cocaine. Then Cynthia Barbare, a dedicated attorney for one of the defendants, demanded the evidence against her client be lab tested, and sure enough -- the substance was high-grade powdered Sheetrock. When word got out, defense attorneys in similar cases had their evidence tested too, and before the wallboard dust settled, charges against 39 defendants were dropped.

Two officers involved in the arrests have been suspended with pay, and a Dallas Police Department investigation is ongoing.