New Delhi, July 24 -- A federal appeals court on Wednesday ruled that President Donald Trump's executive order aiming to curtail automatic birthright citizenship is unconstitutional, blocking its enforcement nationwide. The decision marks a major legal blow to Trump's immigration agenda and could set the stage for another showdown at the US Supreme Court.

In a 2-1 decision, the San Francisco-based 9th US Circuit Court of Appeals upheld an earlier ruling by a federal judge in Seattle, declaring that Trump's directive violated the Citizenship Clause of the 14th Amendment.

"The court agrees that the president cannot redefine what it means to be American with the stroke of a pen," said Washington Attorney General Nick Brown, whose state led...