Supreme Court Justice Brett Kavanaugh launched a series of pointed questions at a Trump administration lawyer about the president’s plan to end birthright citizenship. The shockingly blunt approach during oral arguments Thursday signaled an apparent opposition to the administration’s arguments.

Justice Kagan blasted U.S. Solicitor General John Sauer on the birthright citizenship executive order— which she noted has yet to succeed in any federal court, including cases heard by Trump-appointed judges.

Justice Brett Kavanugh flustered a Trump administration attorney by pressing him for details on how the plan to end birthright citizenship would actually work.