WASHINGTON (AP) — A number of Democratic lawmakers are questioning the legality of a U.S. Border Patrol predictive intelligence program that singles out and detains drivers for suspicious travel inside the country. Sen. Ed Markey of Massachusetts sent a letter Monday to Border Patrol’s parent agency calling the license plate reader program an “invasive surveillance network” that “poses a serious threat to individuals’ privacy and civil liberties” and raised the possibility that the program may run afoul of the U.S. Constitution. “Such pervasive surveillance — similar to surveillance conducted by authoritarian regimes such as China — not only chills lawful expression and assembly but also raises serious constitutional concerns.