Julio Cesar Ayala knew he was taking a risk when he decided to overstay his tourist visa four years ago, but he never expected to be threatened with deportation for climbing behind the wheel of the family's silver minivan. The 53-year-old Salvadoran was stopped by a Baltimore County police officer last year and had to admit that he didn't have a driver's license. Hours after he was handcuffed and separated from his 9-year-old granddaughter on the side of the road, U.S. Immigration and Customs Enforcement received an automatic notification of his arrest through a controversial and burgeoning federal program called...