A deposition is a statement given by a witness under oath and admissible in court. In a deposition by oral examination, lawyers for the other side in a case are present and may cross-examine the witness. Everything that's said is recorded by a stenographer. Evidence, called an "exhibit," may be attached to the deposition; often these are documents supporting or challenging a particular line of questioning. Many times, these documents would not otherwise be made public. Both a deposition and any related exhibits may be entered as evidence in a case.
An affidavit is a statement made under oath. It is a statement of which the person ("affiant") has personal knowledge, but unlike a deposition, does not offer the chance for cross examination or include exhibits.
Depositions have been an invaluable source of information for this site. The lawyers didn't always ask the questions I would have liked answered, but that's made up for by the fact that the person is under oath and, as any lawyer will tell you, lying under oath is a crime. I have found affidavits to be of limited use. They convey little of the sense of a person and are often duplicative. In the O' Keefe case, for example, the stadium commissioners all submitted an identical affidavit. I will publish a few, though, from people for whom a deposition is not available.
O' Keefe v. Gandy, King County Superior Court No. 703099
This was a lawsuit filed by June O' Keefe and Tony Ferrucci, seeking to stop the State of Washington Stadium Commission from naming the Seattle Center as the preferred site for the domed stadium and charging that the Commission acted improperly when picking that site. Most of the court record isn't very interestingthe one exception being a deposition given by commissioner Dave Cohn, where he details his option to become part owner of the Pilots. For more information, see my interview with Dave Cohn.
State of Washington v. American League of Professional Baseball Clubs, Snohomish County Superior Court No. 116038
This is the big one: the lawsuit against the American League over the move of the Pilots and the court records are a goldmine of information. Since the depositions tend to be huge, I've broken them into several pdf files, with separate attachments. Printing these from microfilm is very time-consuming, so I don't have all of the exhibits yet and there are many more depositions to come, but in the meantime, you can read the words of Bud Selig, former Orioles owner, Jerry Hoffberger and former Seattle mayor, Dorm Braman. There will be more in coming months!