In the end, though, it was someone playing by the rules who triggered perhaps the greatest reckoning of Trump’s presidency.

The intelligence official who brought Trump’s misconduct in the Ukraine scandal to light—a CIA member who was detailed to the White House, according to a report in The New York Times—didn’t do it via press leaks, or by passing it to a sympathetic lawmaker. The whistle-blower went instead through the relatively straightforward and unexciting bureaucratic process of filing a complaint with the office of the intelligence community’s inspector general.

Filing the complaint ensured that classified information would be protected, national-security concerns would be evaluated, and ultimately, the information would reach the proper authorities. This candid and somewhat mundane process, while flawed, was surprisingly effective at holding Trump to account.

“The complaint process compels you to specify how you know what you know,” Brian Katz, a former CIA analyst who recently joined the Center for Strategic and International Studies as an intelligence fellow, told me. “When you’re an intelligence analyst, you’re going to deliver truth to power in the most effective manner you can.”

Read: What happened in Ukraine?

The key was its simplicity: By channeling the details of Trump’s misconduct into a formal complaint and then feeding it into the intelligence community’s system, the whistle-blower has thrown a wrench into Trump’s heretofore insurmountable deflect-by-chaos machine. As the scandal escalates, Trump and his White House seem to be in increasing disarray. He released a damaging reconstructed transcript of his July 25 call with Ukraine’s president, which left even some of his Republican allies scratching their heads. He threatened the whistle-blower’s sources in front of a room full of U.S. diplomatic staff. His communications team mistakenly emailed a strategy memo to Democratic lawmakers, then tried to recall the message. His personal lawyer, Rudy Giuliani, who is also implicated in the scandal, has tried to drag the State Department down with him, while also embarking on confusing rants in conversations with reporters.

Despite the White House’s best efforts, the fact that the whistle-blower filed a complaint through proper government channels has made it harder for the usual attacks about traitors and dirty tricks to stick. Michael Atkinson, the inspector general who handled the complaint, and Joseph Maguire, Trump’s recent appointment as acting director of national intelligence, have already come to the whistle-blower’s defense.

As with the Mueller investigation, the broad outlines of the Ukraine scandal had already been playing out in public view. Giuliani had been relatively open about his endeavors to persuade Ukrainian authorities to reopen an investigation into unsubstantiated allegations against Joe Biden and his eldest son’s business dealings in the country. It was no secret on Capitol Hill that the administration had put a mysterious stop on the delivery of military aid to Kiev. With the Mueller investigation, Trump had publicly called on Russia to hack Hillary Clinton’s emails, and shortly after firing FBI Director James Comey, the president admitted in a TV interview that he had done so with “this Russia thing” on his mind. But whereas the Mueller inquiry was sprawling and mired in a cloud of false leads and boundless speculation, the whistle-blower complaint has succinctly laid out its allegations, with lawyer-like precision, in a manner that makes them easy to investigate and harder for Trump to escape. The complaint flagged Trump’s phone call with Ukrainian president Volodymyr Zelensky, which White House aides quickly recognized as problematic. It accused White House lawyers of attempting to hide the call’s transcript on a highly classified server. It raised concerns about Giuliani’s outreach. It identified U.S. officials who could corroborate the details. It has helpful footnotes.