"法官的职权" can be translated into English as "the powers and duties of a judge" or more concisely as "a judge's authority" or "judicial authority of a judge".
"The powers and duties of a judge" is a comprehensive phrase that explicitly mentions both the powers (rights to act) and duties (obligations) of a judge.
"A judge's authority" or "judicial authority of a judge" emphasizes the judge's right or power to make decisions, issue orders, or perform other official acts within the legal system.
Choose the expression that best fits the context and level of formality required.