Territorial sovereignty is established when a State exercises effective, peaceful, and continuous control over a defined territory and is recognized by other States. Recognition by the international community reinforces legitimacy, but is not always legally required if sovereignty is exercised.

How Is Sovereignty Established?
A. Effective Control (Effectivité Principle)
Actual administration: policing, taxation, infrastructure.
Presence of government authority and legal institutions.
Peaceful, public, and continuous possession is essential.
Island of Palmas Case (1928) – Established that effective control trumps discovery or symbolic claims.

How Is Sovereignty Recognized?
A. De Jure Recognition
Legal acknowledgment by other States (often through diplomatic recognition or treaties).
Helps strengthen legitimacy on international platforms (UN, WTO, etc.)
B. De Facto Recognition
Practical acknowledgment of a State’s control, even without full diplomatic ties.
Example: Taiwan is de facto recognized by several countries, but lacks de jure recognition from many due to the One-China policy.

Under international law, territorial sovereignty is grounded in actual control, peaceful administration, and legal authority over territory. Recognition by other States and international bodies reinforces legitimacy but is not strictly essential if effective sovereignty is clear. However, acquisition through force or coercion is illegal under the modern international legal system.