Investigating judge
From France and civil law
Procedure and evidenceCriminal law
What it means
A judge whose job is to investigate a serious crime, gathering evidence for and against the suspect. The judge does not try the case: another court does that.
Why it travels badly
In common-law systems, the police and prosecutors investigate, and judges only decide. A judge who investigates does not fit the adversarial model. And in civil law itself, the role has been cut back or abolished in several countries.
How other systems say it
juge d'instruction
Investigates the most serious crimes, with powers to question witnesses and order searches. It does not decide guilt.
juez de instrucción
A judge who investigates, for most crimes. Spain has long debated moving the investigation to prosecutors.
Staatsanwaltschaft with an Ermittlungsrichter
The investigating magistrate was abolished in 1975. The prosecutor investigates, and a judge only authorises intrusive steps, such as a search or an arrest.
police and the Crown Prosecution Service
The police investigate, the prosecutor decides on the charge, and a judge or jury decides the case.
Tip for translators and students
Do not translate as 'examining magistrate' without an explanation: English readers hear 'magistrate' as a lay judge.
Related: Prosecutor, Magistrate, Jury and lay judges
Updated October 2026. Spotted a mistake? Tell us.
TheLawToKnow Tools’s glossary is an educational overview of the main differences between legal systems. It is not legal advice.
