The new Joe Biden presidential administration may want to move quickly to undo key Trump administration policies involving immigration, labor, abortion and more, but a new U.S. solicitor general may need to proceed more carefully in the U.S. Supreme Court.

The Trump administration quickly reversed litigation positions in a number of cases in 2017, raising questions at the court and more broadly about the duty to defend statutes. A former Justice Department lawyer described the Trump solicitor’s maneuvering to change stances as “aggressive,” and suggested the Biden Justice Department could move just as swiftly to abandon earlier-argued positions in key cases.