Final answer:
Full-time judges are prohibited from practicing law to maintain judicial independence and prevent conflicts of interest, a rule derived from Article III of the U.S. Constitution which ensures judges serve for life during good behavior.
Step-by-step explanation:
A full-time judge must not practice law, which is a principle supportive of an independent judiciary. This is because, under Article III of the U.S. Constitution, federal judges are appointed for life during good behavior, allowing them to operate without political influence and focus solely on ensuring justice.
The idea is to prevent any potential conflicts of interest and maintain the integrity of the judicial system.
Exceptions to this rule might involve certain circumstances, such as representing oneself or one's estate, but generally, serving judges are expected to refrain from practicing law to uphold the ethical standards of the judiciary.
Additionally, while there are no specific constitutional requirements for being a judge such as age or residency, and historically, it was not required for a judge to have prior experience as a lawyer, all current federal judges have graduated from law school, and many have experience as attorneys or state-level judges.