Did President Donald Trump obstruct justice? That is the question that will animate Thursday's Senate testimony by ousted FBI Director James Comey.
The answer contains a legal wrinkle that so far hasn't received much attention.
Relying on a cache of previously confidential notes he kept, Comey is expected to elaborate on private dealings he had with the president related to the Russia investigation. The bureau is looking into whether Trump campaign aides colluded with Russian officials at a time when Moscow was interfering with the U.S. election.