What is characterized as a formal statement given by a witness during legal proceedings?

The term that best describes a formal statement given by a witness during legal proceedings is "testimony." Testimony is provided orally in court or during a deposition, where the witness recounts their observations, experiences, or knowledge relevant to the case. This is a critical component of the legal process, as it allows the parties involved to present evidence and establish facts through the accounts of those who have pertinent information.

In contrast, a deposition, while also a formal statement, typically occurs outside of the courtroom and is taken under oath, but it is not directly given during legal proceedings themselves. An affidavit is another type of sworn statement, but it is written and submitted as evidence rather than delivered in person. An assertion lacks the formal legal status that testimony carries; it simply refers to a declaration or claim, which may not necessarily be given under oath or during legal proceedings. Therefore, testimony is the most accurate choice as it specifically denotes the oral account provided by a witness in the context of legal proceedings.