BRACKETTVILLE, Texas—Kinney County Sheriff Brad Coe joked that his first pop-up driver’s license checkpoint on a rural road would be “boring.” Coe set up on a road that provides smugglers a way around a Border Patrol checkpoint that’s situated between the border and San Antonio. Less than 30 minutes in and with the third vehicle approaching, word came over the radio that the license plate on the incoming black pickup truck was registered to a white pickup truck—an obvious red flag. The driver slowed down briefly as the sheriff flagged him to stop, then gunned it through the checkpoint. Deputy Chris Copland was first in to begin the chase. Several hundred yards later, the black pickup veered off the road, through a fence, and plowed into a ranch through the scrub and brush. Copland followed on foot, along with a Texas Department of Public Safety officer who had arrived a …