Macon County Law Enforcement Center (MCLC) Comprehensive State Practice Exam 2026 - Free Law Enforcement Practice Questions and Study Guide

Impeachment of a witness is a legal process whereby a witness’s credibility is challenged. The correct basis for impeachment in this scenario is prior criminal convictions. This is because the law recognizes that a witness's past behavior, particularly any criminal convictions, can significantly impact their reliability and trustworthiness. Such information is considered relevant to the witness's character for truthfulness, and it may lead jurors to question the witness’s credibility based on their prior actions.

Discrepancies in testimony could also be a valid method for impeachment, as inconsistent statements can raise doubts about a witness's reliability. However, in this question, the focus is specifically on types of established bases for impeachment, with prior convictions being a formal legal ground commonly accepted in court.

Prior knowledge of the case and friendship with the defendant may introduce bias but do not constitute formal grounds for impeachment concerning a witness's reliability in a court of law. These factors might influence a jury's perception, but they lack the direct legal framework that prior criminal convictions provide for questioning a witness's credibility.