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.

The Justices on the Supreme Court wrestled on Thursday with a high-stakes case involving birthright citizenship that’s poised to shape both the Trump Administration’s immigration policy and its attempts to expand presidential power.

The Supreme Court is hearing arguments Thursday morning about the power of lower courts to issue nationwide injunctions, including rulings that have blocked President Donald Trump’s executive order restricting the guarantee of birthright citizenship nationwide.