Final answer:
The code of ethics for a governmental body is related to the rules it sets for conducting business. The U.S. Constitution grants both the House and the Senate the authority to set their own rules, implying they may have established a code of ethics. However, historical records are necessary to pinpoint which institution did so first.
Step-by-step explanation:
The question, 'Which institution instated its first code of ethics?' relates to the ethics and rules that govern the conduct of various governmental bodies in the United States. The answer to this question is not directly provided in the reference material, but we can infer from the given information that the institution likely to have instated a code of ethics first would be guided by its need for rules and the power to enforce them. Section 5 Clause 2 of the Constitution states that both the House and the Senate have the power to establish their own rules for conducting business, which implies that they may have set codes of ethics early in the nation's history. However, specific historical data is needed to identify which of these institutions instated a code of ethics first.