What is a witness's out-of-court testimony that is reduced to writing, usually by a court reporter?

The correct answer is deposition. A deposition is a formal legal proceeding where a witness provides their testimony under oath outside of court, and it is typically recorded in writing by a court reporter. This documentation serves as a vital part of the discovery phase in legal proceedings, allowing both parties to gather information before the trial takes place. The written record produced during a deposition can be used to support or refute claims made in court, making it an essential element of the litigation process.

An affidavit, while also a written statement made under oath, is usually submitted to the court to support a legal argument and is not taken in the context of live testimony. Testimony refers to the evidence presented orally by witnesses during a trial or deposition but does not connote the specific formal process that occurs in a deposition. A certified statement could imply formal recognition or validation of a statement but does not specifically describe the process through which witness testimony is recorded outside of court.