## Facts

- In 1906, the governing authorities for Egypt and the Ottoman Empire agreed on a boundary between Egypt and Palestine and arranged for the line to be marked on the ground, first with telegraph poles and then with masonry pillars.
- After World War I, the League of Nations established Great Britain as the Mandatory power for Palestine (1922), and British authorities surveyed the area and produced official maps reflecting the Egypt–Palestine boundary as administered during the Mandate period.
- In 1948, the Mandate ended and Israel emerged in much of the former Mandate territory; Egypt and Israel then fought and later entered into agreements that culminated in a comprehensive peace settlement.
- In the 1979 Treaty of Peace, Egypt and Israel agreed that the permanent boundary between them would be “the recognized international boundary between Egypt and the former mandated territory of Palestine,” and Israel undertook to withdraw from Sinai to that line while Egypt resumed sovereignty over Sinai.
- A joint peace-treaty commission began demarcation work but could not agree on the precise locations of 14 boundary pillars (out of a larger set of boundary markers) before Israel’s final Sinai withdrawal date in April 1982.
- The unresolved locations included the boundary in the Taba area on the Gulf of Aqaba, where the competing reconstructions would place the coastal resort area on different sides of the boundary.
- After negotiation failed, the parties concluded an Arbitration Compromis (11 September 1986) submitting the dispute over the 14 pillar locations to an ad hoc arbitral tribunal established pursuant to the treaty’s dispute-settlement clause.
- The tribunal examined the 1906 boundary arrangements and demarcation record, later Mandatory and post-Mandate cartography and documents, physical evidence on the ground, and subsequent administrative and governmental practice relevant to the historic boundary line and the disputed pillar sites.

## Issues

1. What does the Treaty of Peace mean by “the recognized international boundary between Egypt and the former mandated territory of Palestine,” and which historic boundary does that clause incorporate?
2. What “critical period” should guide identification of the legally controlling boundary in a demarcation dispute, and how should later materials be used in relation to that period?
3. What evidentiary weight should be given to maps, published materials, and survey products when determining the locations of disputed boundary pillars?
4. To what extent do state succession, acquiescence, de facto agreement, and estoppel limit a party’s ability to argue for a boundary line inconsistent with a line long treated as the boundary in practice?
5. What standard of proof and decision method should the tribunal apply when the historical record is incomplete or conflicting as to precise pillar locations?
6. What limits did the 1986 Compromis place on the tribunal’s authority and on the boundary-marker locations the parties could propose?

## Decision

- The tribunal held that the Treaty of Peace clause refers to the historic Egypt–Palestine boundary established by the 1906 arrangements and expressed on the ground by the demarcation pillars.
- The tribunal treated the 1906–1907 delimitation and demarcation process as central to identifying the boundary line and used later official practice and cartographic material mainly as confirmation where consistent with the historic record.
- Applying a “better claim” approach and a preponderance-of-evidence standard, the tribunal fixed the locations of each of the 14 disputed boundary pillars.
- By a 4–1 majority, the tribunal’s determinations placed the Taba area on the Egyptian side of the boundary, requiring Israeli withdrawal from that area in implementation of the award.

## Legal Principles

- A treaty that defines a boundary by reference to a “recognized international boundary” may incorporate an existing boundary established by earlier instruments and demarcation, rather than authorize a new delimitation.
- In boundary disputes, the “critical period” for evaluating evidence commonly centers on the time when the boundary was created and marked; later conduct can confirm (but does not easily replace) the original boundary.
- Physical demarcation on the ground (pillars and related field records) can be primary evidence of the boundary’s location, especially where later disputes concern marker positions rather than a new boundary claim.
- Maps can be probative depending on their origin, authority, purpose, and consistency with other evidence; official and contemporary maps may carry more weight than unofficial or later compilations.
- Long-standing acceptance of a line in official conduct may support findings of acquiescence or de facto agreement and can, in appropriate circumstances, support estoppel against later inconsistent positions.
- Where conclusive proof of precise marker placement is unavailable, an international tribunal may decide each disputed point on the basis of the “better claim” measured by the preponderance of the evidence.

## Conclusion

Egypt–Israel Arbitration: Taba held that the 1979 peace treaty’s boundary clause incorporated the historic 1906 Egypt–Palestine boundary as marked on the ground, and the tribunal resolved disputed pillar locations using a balance-of-probabilities assessment of the historic demarcation record, maps, and subsequent practice, ultimately placing the Taba area within Egypt.


Egypt-Israel Arbitration: Taba, 27 I.L.M. 1421 (1988)