What is a deposition?published at 19:48 GMT
A deposition is a legal term used in US proceedings where one party is gathering information from a source. It is a witness or party's sworn testimony, given under oath.
In this case, the House Oversight Committee - a small and powerful group of US lawmakers, is administering and supervising.
In today's session, there will be alternating one-hour rounds of questions. The Republicans started, because they have the majority in the committee. Then the Democrats take their turn. And it alternates until the session wraps up.
We're not sure how long today's deposition will last, but one committee member indicated it could go on until 18:00 (23:00 GMT) or later.









