By Ximena Bustillo , Carrie Johnson Mahmoud Khalil, the former Columbia University graduate student known for his role in the 2024 Columbia University pro-Palestinian protests, is now at the center of a legal battle against the Trump administration's deportation policies. Stephanie Keith/Getty Images hide caption Last year, Mahmoud Khalil helped his wife pick out a name for their baby while he sat in immigration detention. For more than 100 days, Khalil waited in immigration custody to learn if he would be allowed to live in the U.S. with his son, whose birth he missed, or be sent to a country he had never lived in. A year after Khalil was detained outside his New York apartment, his legal odyssey continues. The detention last March of Khalil, then a Columbia University graduate student, marked the start of a nationwide effort to deport noncitizens who speak out about Israel's war in Gaza.…