However, international law consistently favors modern state sovereignty, leaving such claims with little chance of success.

Examining similar cases worldwide demonstrates why Malaysia's position on Sabah is legally and historically sound.

Historical precedents in international law often emphasize the necessity for clear legal foundations and the role of territorial sovereignty in resolving disputes. Several cases provide compelling comparisons to the Sulu claim against Malaysia.

The Moctezuma Heirs

One of the earliest and most famous claims similar to the Sulu heirs' involves the descendants of Moctezuma II, the last emperor of the Aztec Empire. After the Spanish conquest of Mexico in 1521, Moctezuma's descendants sought reparations for the seizure of their lands and authority. For centuries, the heirs received a small pension from the Spanish crown as acknowledgment of their lineage, much like the token payments made by Malaysia to the Sulu heirs until 2013.

However, following the independence of Mexico in 1821, these payments ceased. Modern courts rejected the heirs' attempts to reclaim lands or revive their pensions, citing the establishment of Mexico’s sovereignty and the lapse of centuries since the original agreements. The Moctezuma heirs, despite their royal heritage, ultimately lost their claims as they clashed with the principles of statehood and self-determination.

Island of Palmas Case

This dispute between the United States and the Netherlands over the Island of Palmas is a foundational precedent in international law. The arbitrator ruled in favor of the Netherlands, emphasizing effectivités—the actual exercise of authority on the ground—over historical claims. Similarly, Malaysia's continuous administration and effective control over Sabah significantly strengthen its claim, outweighing historical agreements such as the 1878 treaty with the Sultanate of Sulu.

Western Sahara Advisory Opinion

In this case, the International Court of Justice (ICJ) assessed whether Western Sahara was terra nullius (no man’s land) at the time of Spanish colonization and whether Morocco or Mauritania had legal ties to the region. The ICJ recognized some historical ties but noted that they did not justify sovereignty claims, prioritizing the principle of self-determination. This principle undermines the Sulu claim, as the people of Sabah have expressed their will through democratic processes, affirming their desire to remain part of Malaysia.

Ligitan and Sipadan Case

This territorial dispute between Malaysia and Indonesia involved two islands off Borneo. The ICJ ruled in favor of Malaysia, again focusing on effectivités. It highlighted Malaysia's consistent regulation of the area, such as wildlife conservation, as proof of effective control. This ruling reinforces Malaysia's sovereignty over Sabah, as Malaysia has continuously governed and developed the region for decades.

The Mapuche Struggle

The Mapuche Aboriginal people of Argentina and Chile provide another example of how historical grievances have evolved in the modern era. As indigenous inhabitants of Patagonia, the Mapuche faced displacement and marginalization during the 19th-century campaigns to consolidate Argentina and Chile as nation-states.

Unlike the Sulu heirs, the Mapuche have focused their efforts on gaining cultural and political recognition rather than asserting sovereignty or seeking monetary compensation for historical losses. Despite persistent activism, their claims for autonomy and reparations have been limited to symbolic gestures, such as recognition of land rights in specific regions.

This demonstrates the stark reality for historical claimants: modern nation-states, backed by international law, prioritize territorial integrity and sovereignty over historical grievances. If the Mapuche, with their deep-rooted cultural identity and presence, cannot reclaim their lands, the Sulu heirs—who no longer reside in or govern Sabah—face an even slimmer chance.

Indigenous Claims in the United States and Canada

The situation in North America offers further insight into how such cases are addressed. Indigenous tribes in the United States and Canada have pursued legal avenues to reclaim lands or secure financial settlements for past injustices. While some cases have resulted in compensation or restoration of land rights, these outcomes are limited to territories within the existing borders of the countries in question.

For example, Native American tribes in the United States have occasionally won settlements from the government, but these have been limited to rectifying violations of treaties. In Canada, indigenous groups have successfully negotiated agreements granting them autonomy over certain lands, but not sovereignty. Crucially, these cases occur within a framework that recognizes state sovereignty, making the Sulu heirs’ attempt to assert external claims over Sabah fundamentally different and far less viable.

Lessons for the Sulu Case

The recurring theme across these examples is the dominance of modern state sovereignty and the principle of non-retroactivity in international law: past agreements cannot override the established legal status of nation-states.

Malaysia’s sovereignty over Sabah is reinforced by the1963 Referendum: The people of Sabah voted to join Malaysia, an act recognized by the United Nations and the international community. This decision supersedes any historical agreements between the Sulu Sultanate and colonial powers. The inclusion of Sabah into Malaysia reflects the will of its people, an act of Self-Determination, which outweighs hereditary claims by non-resident individuals.

Over a century has passed since the 1878 agreement: the principle of laches in international law argues against reviving ancient claims, especially when no sustained assertion of rights occurred for decades.

The cases of the Moctezuma heirs, the Mapuche, and indigenous peoples worldwide demonstrate the futility of pursuing outdated claims against sovereign states. Even if historical grievances have merit, modern legal systems prioritize stability and the established order. These cases demonstrate that historical agreements alone, especially those involving pre-colonial or colonial contexts, rarely hold weight in modern international law unless paired with effective administration and the will of the affected population. The Sulu heirs’ claim relies on a loosely defined historical treaty, which international law generally views as secondary to established sovereignty through effective governance. Malaysia’s consistent development and administration of Sabah thus stand as compelling legal defenses.

The Sulu heirs, who no longer reside in Sabah or hold any governance over it, are pursuing a claim that lacks any legal basis under international law. Their case has been further weakened by the questionable arbitration process, which Malaysia has successfully contested in other jurisdictions.

While the Sulu heirs may frame their claim as a quest for justice, the realities of international law and historical precedent render their efforts unlikely to succeed. Malaysia stands firmly on the side of modern state sovereignty, with legal, historical, and moral principles supporting its position.

The fate of similar claims around the world underscores this conclusion: historical grievances cannot override the legal rights of nation-states. Malaysia's sovereignty over Sabah is unshakable, and the Sulu heirs’ claim is destined to remain a historical footnote.