A veteran immigration lawyer in San Francisco is part of the team building the case for Mahmoud Khalil. He’s one of the pro-Palestinian student activists the Trump administration is trying to deport. Khalil has a green card, but for nearly two months, he’s been locked in immigration detention. The case has sparked national attention, but as KQED’s Senior Immigration Editor Tyche Hendricks reports, it’s not totally uncharted legal territory.