testifies

Testifies is the third-person singular present tense of the verb testify. To testify is to give evidence under oath, typically in legal settings such as trials or depositions, or to bear witness to a fact or event.

In law, testimony may be oral, given in court during direct and cross-examination, or written, such as affidavits or declarations. A witness must usually be sworn or affirmed to provide legally admissible testimony; failure to tell the truth can subject the witness to perjury. The rules of evidence govern what testimony may be offered and how it may be evaluated, including issues of competency, relevance, credibility, and hearsay.

In broader usage, "testifies to" can describe evidence or support for a claim, as in "the data testifies to the effectiveness of the treatment." The term derives from Latin testificari, via Old French testifier, from testis "witness."