President Donald Trump thought he had a good idea: With the flick of a pen, he could sign away the constitutional right to citizenship granted to nearly everyone who is born in the United States, in an attempt to curb illegal immigration. He was very proud of the idea.

“It was always told to me that you needed a constitutional amendment. Guess what? You don’t,” a gleeful Trump told Axios’ Jonathan Swan when asked about his desire to end the practice of birthright citizenship, which is based on a longstanding interpretation of the 14^th amendment’s classification of all persons born or naturalized in the United States “and subject to the jurisdiction thereof” as citizens.