## Facts

- The dispute concerned sovereignty over the Aouzou Strip, a narrow band of desert territory along the Libya–Chad border.
- After Libya became independent from Italy and Chad became independent from France, the two states disagreed about the location of their common frontier and which state held title to the Aouzou Strip.
- Chad maintained that the boundary was already fixed by the 1955 Treaty of Friendship and Good Neighbourliness between France and Libya, under which Libya recognized the frontiers of France’s African possessions as set out by instruments referenced in the treaty.
- Libya contended that the 1955 treaty did not determine the boundary at issue and further argued the treaty was invalid because the Libyan king had been coerced into signing it.
- The 1955 treaty included a clause allowing either party to terminate the treaty after 20 years, which Libya invoked to argue the arrangement could not permanently settle a boundary.
- Diplomatic efforts did not resolve the disagreement. Libya occupied the Aouzou Strip by force and later conducted military operations in parts of Chad, including areas within and outside the Strip.
- Chad brought the situation to the attention of the U.N. Security Council and sought Libya’s withdrawal.
- In 1989 Libya and Chad concluded a framework agreement to seek a political solution within a year and, if unsuccessful, to submit the dispute to the International Court of Justice (ICJ).
- After negotiations failed, the parties seised the ICJ and asked it to determine the location of their boundary and, by implication, sovereignty over the Aouzou Strip.

## Issues

1. Whether the 1955 Treaty of Friendship and Good Neighbourliness between France and Libya validly established the international boundary between Libya and the territory that became Chad, including the allocation of the Aouzou Strip.
2. Whether Libya’s allegations of coercion or the treaty’s termination clause prevented the treaty from having binding effect as a boundary settlement.
3. If the 1955 treaty did not settle the boundary, whether other considerations—such as historical claims and effectivités (acts showing actual exercise of authority)—could determine title to the disputed territory.

## Decision

- The ICJ held that the 1955 Franco‑Libyan treaty validly established a complete and binding frontier for the relevant area, as identified through Article 3 and the instruments referenced in the treaty’s annex.
- The Court rejected Libya’s challenge to the treaty’s validity; the alleged coercion was not established to a standard that could invalidate the treaty under international law.
- Applying the treaty framework, the Court determined that the Aouzou Strip lay on the Chadian side of the boundary and that Chad held sovereignty over the disputed territory.
- The Court treated the treaty boundary as decisive and found that later conduct or asserted effectivités could not displace a clear treaty-based boundary.
- The judgment was adopted by 16 votes to 1.

## Legal Principles

- A valid treaty that defines or recognizes an international boundary is controlling for determining title between the parties.
- Boundary provisions have a lasting character: termination, expiry, or change in other treaty obligations does not, without clear agreement, undo a boundary settlement.
- A successor state may rely on boundary arrangements established for the territory it inherits, and independence does not reopen a settled frontier.
- Claims that a treaty is invalid due to coercion require proof meeting the requirements of international law; unsupported assertions do not defeat treaty title.
- Effectivités generally matter most where legal title is absent or unclear; where treaty title is clear, effectivités cannot override it and at most may confirm the result.

## Conclusion

Libya v. Chad resolved the Aouzou Strip dispute by treating the 1955 Franco‑Libyan treaty as a binding boundary settlement: the ICJ found the treaty valid, interpreted it as fixing a complete frontier, and concluded that the Aouzou Strip is Chadian territory, leaving Libya’s later occupation and other acts unable to change the treaty-based allocation of sovereignty.


Libya v. Chad, 1994 I.C.J. 6 (Feb. 3)