This is a central and highly debated question in international relations and international law.

There are compelling arguments on both sides:

Argument for Rules Remaining Constant (Regardless of Power Shifts)-

This perspective emphasizes the foundational principles of international law and the dangers of a constantly shifting legal framework.

• Predictability and Stability: The primary purpose of law is to create order and predictability. If international law is constantly reinterpreted based on the power of individual states, it loses its objective nature and becomes a tool of convenience for the powerful. This would lead to a chaotic and unstable international system where no state, regardless of its size, could rely on established norms.

• Sovereign Equality: A core tenet of international law, enshrined in the UN Charter, is the sovereign equality of states. While real-world power disparities exist, the legal fiction of equality is crucial for small and medium-sized states to have any voice or protection against larger powers. Reinterpreting law based on power would undermine this principle, making weaker states perpetually vulnerable.

• Rule of Law vs. Rule of Power: Adherents to this view argue that international law should embody the "rule of law," where even the most powerful states are bound by the same rules. If rules can be bent or broken by powerful states with impunity, it effectively becomes the "rule of power," where might makes right, leading to a more dangerous world.

• Preventing Anarchy: A stable framework of international law is seen as essential to preventing international anarchy. If the law is perceived as merely reflecting the current power balance, it provides little incentive for powerful states to adhere to it when their interests diverge, potentially leading to increased conflict.

• Normative Force: The legitimacy and normative force of international law derive from its perceived fairness and universality, not from the fleeting power of specific actors. Allowing powerful states to unilaterally reshape the law would erode this legitimacy.

• Precedent: Reinterpreting law for one rising power would set a precedent for others, leading to a perpetual cycle of legal re-negotiation as power dynamics shift.

Argument for Reinterpreting/Adapting International Law (in Light of Power Shifts)-

This perspective acknowledges the dynamic nature of international relations and the need for law to remain relevant and effective.

• Realism and Effectiveness: Proponents of this view argue that international law, to be effective, must reflect the realities of global power. If rising powers feel that the existing legal framework does not adequately represent their interests or accommodate their capabilities, they may choose to disregard it, rendering the law ineffective.

• "Great Power Responsibility": Some argue that rising powers, like China, should take on greater responsibility for global governance and rule-making commensurate with their increased influence. This might necessitate adjustments to existing legal frameworks to allow for their greater participation and buy-in.

• Evolving Norms and Customary Law: International law is not static; it evolves through treaties, state practice, and opinio juris (acceptance of a practice as law). As new powers emerge and their practices become more influential, this naturally contributes to the development of customary international law. This is a dynamic process inherent to international law.

• Addressing Historical Inequities: Some rising powers might argue that current international law reflects a historical order dominated by Western powers and may seek reinterpretation to address perceived biases or inequities in areas like economic governance, human rights, or the use of force.

• Avoiding Obsolescence: Legal frameworks that are too rigid risk becoming obsolete and irrelevant in a rapidly changing world. A degree of flexibility and adaptation is necessary for international law to remain a living system capable of addressing new challenges (e.g., cyber warfare, climate change, outer space governance).

• China's Approach: China often expresses a desire for a "more just and equitable" international order, implying a critique of the current system and a wish for reforms that reflect its growing influence. While it generally advocates for multilateralism and adheres to many existing international laws (especially when it serves its interests, like trade), it also selectively interprets or challenges norms that it views as encroaching on its sovereignty or national interests (e.g., in the South China Sea, human rights).

Conclusion

The prevailing view among mainstream international lawyers is that the fundamental principles and rules of international law should remain constant and universally applicable, regardless of power shifts. This is seen as crucial for maintaining stability, predictability, and the legitimacy of the international legal order.

However, it's also acknowledged that international law is not static. Adaptation and evolution are necessary, primarily through established mechanisms like treaty renegotiation, the development of new customary international law (driven by state practice and opinio juris), and the interpretation of existing treaties by international courts. The challenge lies in distinguishing legitimate evolution from unilateral reinterpretation driven purely by power interests, which would undermine the very fabric of international law.

The tension arises when powerful states, like China, interpret existing rules in ways that deviate significantly from the consensus of other states, or when they seek to assert new norms that are not widely accepted. The maritime disputes in the Taiwan Strait and South China Sea are prime examples of this tension, where China's expansive claims are consistently challenged by other states asserting existing international law.