Although Bolton is now free from Trump, having left the White House in September after 17 months on the job, he faces a similar challenge in the Ukraine investigation, which is shaping up to be in part about the president’s authority over foreign policy. Bolton again has to decide whether to give up on long-held beliefs—this time about the power of the presidency—to be popular in Washington. Of course, subpoenas have a way of making decisions easier. Bolton could just go along to get along, deciding to exact some revenge on Trump with a deposition filled with a detailed litany of any presidential crimes and misdemeanors.

But subpoenas rarely change anyone’s mind, let alone one as disciplined and devoted as Bolton’s. The power of the modern presidency is Bolton’s career legacy, a project he has been working on longer than North Korea, Iran or any one issue. When Trump and his defenders question the legitimacy of today’s inquiry, they’re not just speaking Bolton’s language—they’re using his talking points. Even if Bolton soured on Trump or disagreed with his Ukraine scheme, the current resident of the White House is unlikely to have changed the former national security adviser’s belief that the United States needs a strong commander in chief.

For that reason, Bolton’s decision to consider providing a deposition is as momentous as it surely was tortured. His testimony will likely be the same.