An adverse witness is a witness who is called to give testimony during a trial or similar legal proceeding, but provides information that is contrary to the desired testimony of the side that called him or her. In most legal cases, the lawyer who calls a witness to testify cannot use leading questions during testimony nor can he or she try to discredit his or her own witness. An adverse witness who provides information that could be damaging to the side that called that witness to testify, however, can be asked leading questions by the lawyer that called the witness in an attempt to discredit his or her testimony.
Sometimes also called a hostile witness, an adverse witness is one of a few special cases in which one side in a legal dispute can act against its own witness. Most witnesses in a legal proceeding are called by one of the two sides of a case — the prosecution, or plaintiff, or the defendant. The lawyer representing the side that calls the witness is typically not allowed to ask leading questions of that witness. Lawyers are also not usually allowed to try to discredit their own witnesses.
When a witness called by one side of a case provides information or testimony that is potentially damaging to that side, however, then he or she may be deemed an adverse witness. The lawyer that called the witness may request of the presiding judge to allow him or her to treat the witness as a hostile or adverse witness. Once this is granted, the lawyer may attempt to discredit the witness. This can include the use of leading questions intended to disprove what the witness has said or otherwise invalidate the witness’s testimony.
While this process may occur during the initial testimony and direct examination of a witness, lawyers can also call an adverse witness back for further testimony to discredit the witness’s previous comments. This is somewhat similar to the establishment of a person as an “unfavorable witness,” which typically indicates that a witness provides information that may be indirectly harmful to the side that called him or her to testify. Unlike a situation dealing with an adverse witness, however, a lawyer is not usually allowed to effectively “cross-examine” his or her own unfavorable witness, but can provide further evidence that contradicts the information provided by that witness.
