White Paper – 10/7/25

Why Thailand Cannot Unilaterally Cancel the Border MoUs with Cambodia

By Attorney Samantha Yem
For Publication in Khmer Times

Introduction

Recent statements from Bangkok suggesting a referendum to cancel existing Memoranda of Understanding (MoUs) with Cambodia on border issues have raised deep concern. These MoUs, signed in good faith between our two nations, form the legal and diplomatic foundation for peaceful border demarcation.

This white paper explains why, under international law, Thailand cannot unilaterally cancel these agreements. It also highlights the potential consequences of such an action for bilateral relations, ASEAN stability, and international order.

The Legal Nature of MoUs

Although styled as ‘MoUs,’ these instruments regulate territorial boundaries. In international law, agreements concerning sovereignty and borders are treated with the same weight as formal treaties. The content, not the title, determines the binding legal effect.

International Legal Framework

– Vienna Convention on the Law of Treaties (1969):
– Article 26 (Pacta Sunt Servanda): “Every treaty in force is binding upon the parties and must be performed in good faith.”
– Article 27: A country cannot rely on domestic law—including referenda or constitutional amendments—as justification for not performing an international agreement.
– Article 62: Even in cases of fundamental change of circumstances, boundary treaties are expressly excluded from unilateral termination.

– ICJ Precedent: The International Court of Justice has consistently upheld the permanence of boundary agreements.
– Temple of Preah Vihear Case (1962, 2013): Confirmed that maps and agreements are binding, and Thailand cannot unilaterally alter borders.
– Burkina Faso v. Mali (1986): The Court emphasized that stability of boundaries is a cornerstone of international law.

Why a Thai Referendum Has No Legal Effect

A domestic referendum in Thailand cannot alter Cambodia’s legal rights. International law is clear: domestic politics do not override international obligations. Any unilateral cancellation of the MoUs would be invalid internationally.

If Thailand were to act upon such a referendum—by disregarding agreed maps or moving military units into disputed zones—it would constitute a violation of Cambodian sovereignty and a breach of the United Nations Charter.

Strategic and Regional Implications

1. Bilateral Tensions: A referendum risks inflaming border disputes, undermining decades of diplomacy.
2. ASEAN Stability: Unilateral cancellation of border agreements contradicts ASEAN’s core principle of peaceful settlement of disputes.
3. Global Precedent: Allowing one country to cancel a border agreement unilaterally would destabilize international order everywhere, not just in Southeast Asia.

Conclusion

Thailand’s proposed referendum has no basis in international law. The MoUs between Cambodia and Thailand remain valid, binding, and enforceable. Cambodia has the full support of international law, ASEAN principles, and ICJ jurisprudence.

The Kingdom of Cambodia remains committed to peaceful dialogue, regional stability, and good neighborly relations, but it will also defend its sovereignty vigorously against any attempt to undermine it.

By Attorney Samantha Yem
For Khmer Times

Thailand’s Legal Threats Against Cambodia: Legal Analysis and Strategic Recommendations

By: Attorney Samantha Yem
Attorney Bernard Scott Bolls

Prepared by: SK Law Office, Phnom Penh & Washington D.C.

Date: August 7th, 2025

Executive Summary

This white paper examines the recent announcement by Thailand’s Acting Prime Minister Phumtham Wechayachai regarding plans to initiate domestic and international legal action against the Kingdom of Cambodia. It provides a legal analysis of Thailand’s jurisdictional standing, evaluates the strength of its claims, and outlines strategic legal and diplomatic recommendations for Cambodia to safeguard its national interests.

Background

On August 6, 2025, Thai Acting Prime Minister Phumtham Wechayachai instructed relevant government departments to prepare legal documents for potential criminal and civil litigation against Cambodia. This announcement follows recent tensions between both nations stemming from border disputes, military movements, and the alleged violation of a ceasefire agreement brokered on July 28, 2025.

I. Legal Analysis of Thailand’s Standing

1. Jurisdictional Limits

Thailand cannot exercise unilateral jurisdiction over Cambodia or its officials for acts committed on Cambodian territory. Under international law, particularly the principles of sovereign immunity and territorial integrity, no state may subject another sovereign nation to its domestic legal system without a recognized legal basis. International forums such as the ICJ require mutual consent, which Cambodia has not provided.

2. Treaty and ICJ Precedents

The 1962 and 2013 rulings by the International Court of Justice (ICJ) firmly established Cambodia’s sovereignty over the Preah Vihear Temple and surrounding areas. Thailand’s claims to these or nearby territories lack legal foundation and risk contradicting their own prior commitments to international adjudication.

3. Weaknesses in Thailand’s Legal Position

– The ceasefire violations reported on July 28, 2025, cast doubt on Thailand’s good faith.
– The absence of legal jurisdiction over Cambodian territory undermines the legitimacy of any Thai domestic court action.
– Thailand’s invocation of legal channels appears politically motivated rather than rooted in international legal obligations.

II. Thailand’s Possible Legal and Political Strategies

Thailand may adopt the following approaches to assert its claims:
– File symbolic lawsuits in domestic courts for political impact.
– Attempt to initiate a new ICJ case or request an advisory opinion via the UN General Assembly.
– Appeal to ASEAN mechanisms under the ASEAN Charter to seek regional diplomatic pressure.
– Submit complaints to the United Nations Security Council or General Assembly.

III. Strategic Legal and Diplomatic Recommendations for Cambodia

– Publicly reaffirm ICJ rulings on Cambodian territorial sovereignty.
– Refuse to recognize the jurisdiction of Thai domestic courts over Cambodian entities or nationals.
– Propose third-party monitoring of disputed territories by UN or ASEAN observers.
– Prepare counter-diplomatic notes and legal documentation to international bodies.
– Launch a public diplomacy campaign including legal white papers, op-eds, and official statements.

Conclusion

Thailand’s announcement to pursue legal action against Cambodia is legally tenuous and strategically aggressive. Cambodia must act swiftly and strategically to uphold its sovereignty, counter Thailand’s narrative, and preserve regional peace through legal diplomacy. The Kingdom’s adherence to international law and commitment to peaceful resolution must be consistently highlighted across all diplomatic channels.

Attorney Bernard Scott Bolls & Attorney Samantha Yem
SK & SCOTT LAW FIRM
Washington, D.C.

The Temple, The Treaty, The Truth

A White Paper on the Cambodia–Thailand Border Dispute and the Role of International Law

Date: June 13, 2025

Prepared by:

Attorney Bernard Scott Bolls & Attorney Samantha Yem
SK & SCOTT LAW FIRM
Washington, D.C.

The Temple as National Soul

To the Cambodian people, the Temple of Preah Vihear is more than ancient stone. It is a sacred embodiment of national memory, cultural identity, and sovereignty. Perched atop a mountain with sweeping views of the Cambodian plains, the Temple stands as a timeless symbol of Khmer civilization. To see it questioned once again is not just a legal affront—it is a reopening of a historical wound that many Cambodians hoped had long healed.

Historical Context

The Preah Vihear Temple lies near the border between Cambodia and Thailand. Its territorial affiliation was settled through the 1904 and 1907 Franco–Siamese treaties. The 1962 ruling of the International Court of Justice (ICJ) awarded sovereignty over the Temple to Cambodia, based on the Annex I map accepted by Thailand for decades. Despite this, disputes over an adjacent 4.6 km² zone have periodically resurfaced, including armed conflict in 2008–2011 and, more recently, inflammatory claims by Thai officials.

Legal Framework

The ICJ ruled in 1962 that the Temple is situated in Cambodian territory. This was reaffirmed in 2013, when the Court interpreted the 1962 judgment to also grant Cambodia sovereignty over the immediate vicinity. Both rulings are binding under the UN Charter. Thailand’s repeated objections not only challenge Cambodia’s rights, but also undermine the credibility of the international legal system.

Recent Developments

Political statements made by Thai lawmakers in early 2025 have rekindled public disputes over Preah Vihear, with implications that Cambodia does not have legitimate sovereignty. This has led to growing concerns of military mobilization and social unrest in border regions. Cambodia continues to urge peaceful resolution and respect for past rulings. However, these statements are dangerous and risk violating ASEAN’s commitment to peace and non-aggression.

Strategic and Geopolitical Importance

This issue is not merely bilateral—it is a test of the international community’s commitment to upholding law over force. If established ICJ rulings can be questioned without consequence, global norms lose meaning. For the Indo-Pacific region—where the rules-based order is already under strain—this case is a bellwether. The United States has a historic role in defending international law. Supporting Cambodia’s legal victory is not just about justice—it is about maintaining global stability and credibility.

Why It Matters to the United States

America’s leadership in the Indo-Pacific depends on its credibility in defending international norms. Cambodia is a small country asking that its legal rights be honored. If international judgments can be ignored, how can any country—big or small—be secure? Upholding the rule of law at Preah Vihear demonstrates America’s commitment to justice, not just rhetoric.

Call to Action

We respectfully call upon the United States government, legal institutions, think tanks, and media outlets to: stand firm in defending the principles of international law, uphold the sovereignty of smaller nations, support peaceful dispute resolution through impartial judicial bodies such as the ICJ, and ensure fair and balanced reporting that amplifies the voices of those advocating for justice, stability, and rule of law in Southeast Asia and beyond.