Final answer:
In the field of Law, when the agent must put the interests of the principal above the interests of the agent or any third party, it is known as the fiduciary duty.
Step-by-step explanation:
In the context of the question, the subject is Law.
When the agent must put the interests of the principal above the interests of the agent or any third party is a fundamental principle known as the fiduciary duty in the field of law. Fiduciary duty refers to the legal obligation of the agent (also known as the fiduciary) to act in the best interests of the principal (the person they are representing) and not prioritize their own interests or those of any other party.
For example, in the case of Glasser v. United States, the court ruled that a defense lawyer's conflict of interest arising from a simultaneous representation of codefendants violates the Assistance of Counsel Clause of the Sixth Amendment, highlighting the importance of putting the principal's interests first.