In United States constitutional law, which statement about interstate compacts between states is generally true?

Introduction / Context:
Interstate compacts are agreements between two or more states in the United States to cooperate on matters of common concern, such as water sharing, transportation or environmental standards. These compacts are recognised in the United States Constitution and are an important tool in federalism. This question asks which statement about interstate compacts is generally true, focusing on the role of Congress and the nature of such agreements.

Given Data / Assumptions:

• The subject is interstate compacts between states in the United States.
• The options discuss foreign states, the number of states, the role of Congress and agreements with foreign countries.
• We assume the constitutional rule that states may enter compacts with the consent of Congress.
• The aim is to pick the statement that correctly reflects this constitutional requirement.

Concept / Approach:
Article I, Section 10 of the United States Constitution states that no state shall enter into any agreement or compact with another state or with a foreign power without the consent of Congress. In practice, Congress has authorised many interstate compacts, especially those that could influence the federal balance or affect other states. Interstate compacts often involve more than two states, for example, regional environmental or transportation agreements. Most compacts are between states themselves, not between the national government and foreign nations. Therefore, the correct statement is that Congress generally must approve interstate compacts, especially those with significant policy impact.

Step-by-Step Solution:
Step 1: Examine option C, which says that Congress generally must approve interstate compacts. This matches the constitutional rule that such agreements require consent from Congress. Step 2: Option A claims that states may freely form compacts with foreign states without federal consent, which contradicts the Constitution. Step 3: Option B states that compacts may involve no more than two states, but in reality many compacts include three or more states. Step 4: Option D suggests that most interstate compacts are between the national government and foreign countries, which is incorrect because interstate compacts are defined as agreements between states. Step 5: Since only option C reflects the correct constitutional principle, it is the correct answer.

Verification / Alternative check:
To verify, consider well known examples such as the Port Authority of New York and New Jersey, which is an interstate compact agency created with the consent of Congress. Many water compacts in the western United States, involving multiple states sharing rivers, were also approved by Congress. Legal discussions of these compacts frequently mention that they are valid because Congress approved them under the constitutional requirement. This confirms that Congressional consent is a key element, supporting option C as the true statement about interstate compacts.

Why Other Options Are Wrong:
Option A is wrong because states cannot simply form compacts with foreign states without federal oversight; the Constitution requires federal consent for agreements with foreign powers.

Option B is wrong because interstate compacts can involve more than two states; some regional compacts include several states working together.

Option D is wrong because interstate compacts are specifically agreements between states, not between the national government and foreign nations.

Common Pitfalls:
Students sometimes misunderstand the term compact and assume it might cover any agreement, including those made by the national government with other countries. Others may think that small agreements between neighbouring states do not require any federal involvement. To avoid these errors, remember that interstate compacts are defined as agreements between states and that the Constitution gives Congress an important oversight role. Knowing this principle is useful in understanding how cooperative federalism operates in areas like transportation, natural resources and environmental protection.

Final Answer:
Congress generally must approve interstate compacts when they affect the balance of power in the federal system.