The Supreme Court has thrown out Trump's order ending birthright citizenship, a major defeat for one of his signature second-term policies.

• In a 6-3 ruling, the court said anyone born on US soil is automatically a citizen, and the president cannot change that by executive order.
• The order would have denied citizenship to babies born in the US to parents here illegally or only on temporary visas; it never took effect and lower courts had already blocked it.
• The decision rests on the 14th Amendment and a 128-year-old precedent (Wong Kim Ark) that birth on US soil makes you a citizen regardless of a parent's immigration status.
• The lineup crossed party lines: liberal and conservative justices joined the majority, while Thomas, Gorsuch, and Alito dissented, arguing the amendment was meant only for freed slaves.
• Kavanaugh agreed the order had to fall but hinted Congress, not the White House, might have room to change the rule through legislation.

Outlook: Birthright citizenship stays in place for now, but the door is open for a future fight in Congress.