Federal Judge Aileen Cannon on Monday dismissed Donald Trump’s classified documents indictment, ruling that special counsel Jack Smith had been unconstitutionally appointed. If Cannon’s stunning decision withstands appeal, it would end what had long been considered the strongest and most “airtight” case against the former president. It involved Trump’s willful retention of top-secret documents after he left the White House and his repeated refusals to return the classified records. As my colleague Pema Levy wrote, Cannon has spent much of the past two years issuing unprecedented decisions that have shocked legal scholars, each of which has helped Trump dodge accountability. The ex-president was lucky that Cannon got assigned this case—but he also helped make his own luck by putting her on the bench.