Castillo, a former civil rights attorney and the first Hispanic chief judge in the Northern District of Illinois, has long hinted at his dissatisfaction with the tactics used in the stings, a staple of the ATF playbook since the mid-1990s that uses the promise of a big score to target what are supposed to be dangerous criminals. In reality, the stash houses — as well as the drugs, cash and armed guards purportedly inside — were dreamed up by agents.