In law, cross-examination is the interrogation of a witness called by one's opponent. It is preceded by direct examination (in England, Australia and Canada known as examination-in-chief) and may be followed by a redirect (re-examination in England, Australia, and Canada).
In the United States, the cross-examining attorney is typically not permitted to ask questions which do not pertain to the facts revealed in direct examination. This is called going beyond the scope of the direct examination. This does not apply in England, Australia, and Canada, where once a witness is called the opponent's lawyer can ask any question relevant to the issues in the trial.
Unlike in direct examinations, however, leading questions are typically permitted in a cross-examination, since the witness is presumed to be unsympathetic to the opposing side.
The main purposes of cross-examination are to elicit favorable facts from the witness, or to impeach the credibility of the testifying witness to lessen the weight of unfavourable testimony. Cross-examination frequently produces critical evidence in trials, especially if a witness contradicts previous testimony. The advocate Edward Marshall-Hall built his career on cross-examination which often involved histrionic outbursts designed to sway jurors.