Chief Justice John Roberts Jr. once again on Tuesday appeared to be the justice in the middle of a Supreme Court divided over a controversial Trump administration policy. But questions from Trump appointee Neil Gorsuch suggested he was searching to find a hole in the administration’s defense of its decision to end a program that has allowed nearly 700,000 “Dreamers” temporarily to work, receive driver’s licenses and renewable two-year protection from deportation.

During more than an hour of arguments Tuesday, Gorsuch was first to ask a key question of U.S. solicitor general Noel Francisco that quickly became central to the positions of both sides: Did the Department of Homeland Security, in deciding to rescind the Obama-era program in 2017, adequately consider the “reliance interests” formed by the Dreamers and others in a program that has existed since 2012?