Voir dire (; often ; from an Anglo-Norman phrase meaning "to speak the truth") is a legal phrase for a variety of procedures connected with jury trials. It originally referred to an oath taken by jurors to tell the truth (Latin: verum dicere). This term is also used informally to describe the practice of jury selection in certain jurisdictions.

The term "voir dire" comes from the Anglo-Norman language, with "voir" deriving from Latin verum, meaning "[that which is] true." The phrase has historically been used in legal contexts, particularly in relation to jury selection and determining the admissibility of evidence or competency of witnesses or jurors.

In Commonwealth countries, Ireland, and Hong Kong, a voir dire refers to a "trial within a trial" and is a hearing to determine the admissibility of evidence or competency of witnesses or jurors.

In the United States, voir dire is the process of questioning prospective jurors about their backgrounds and potential biases, as well as examining the qualifications of expert witnesses. The process of jury selection and managing voir dire is a crucial area of study for criminal trial attorneys, with organizations such as the Center for Jury Studies and the American Bar Association conducting research on the subject.