EEZ Due Regard and Peaceful Purposes Explained

Created: 22 April 2025

In the exclusive economic zone (EEZ), UNCLOS preserves core freedoms of navigation and overflight for all States, including operational uses associated with those freedoms. Those freedoms are not absolute. UNCLOS imposes a treaty duty of due regard toward the coastal State’s EEZ rights and duties, and it requires compliance with coastal-State laws that are consistent with the Convention. UNCLOS also applies the Convention’s high-seas peaceful-use constraints, anchored in the U.N. Charter, to EEZ conduct. In operational terms, the legal posture is stable: presence and transit are generally permitted; unreasonable interference, compulsion signaling, and unsafe conduct are constrained by due regard, coastal-State resource rights, and the Charter-based prohibition on threat or use of force.^{1 2}

1. Treaty Baseline: EEZ Freedoms in System Context

UNCLOS establishes the EEZ as a zone in which the coastal State holds specific sovereign rights over resources and certain forms of jurisdiction. Other States, however, retain defined freedoms tied to navigation and overflight. In the EEZ, the Convention preserves for other States the high-seas freedoms of navigation and overflight and “other internationally lawful uses of the sea related to these freedoms.” The Convention then adds controlling constraints: in exercising those rights, States “shall have due regard” to the coastal State’s rights and duties and “shall comply” with coastal-State laws and regulations adopted in accordance with the Convention.³

UNCLOS does not convert the EEZ into a territorial sea. Nor does it grant the coastal State territorial-sovereignty-type control over foreign ships and aircraft. Such control is limited only to the Convention’s defined EEZ rights and jurisdiction. At the same time, UNCLOS does not treat the EEZ as a legal vacuum. The operational legality of an action in the EEZ depends on whether it falls within the Convention’s preserved EEZ freedoms and whether it is conducted with due regard, without unreasonable impairment of coastal-State EEZ rights, and consistently with Charter-based peaceful-use constraints.^{4 5}

Coastal-State jurisdiction in the EEZ includes defined enforcement authority in specified subject areas. Enforcement powers are not general police powers over routine navigation and overflight, but they are real where conduct implicates EEZ living resources, applicable pollution-control standards, or marine scientific research conducted under the Convention’s EEZ framework. Commanders and operators should assume that boarding, inspection, detention, and proceedings may be asserted in those categories to the extent the Convention authorizes them.⁶

2. Due Regard: A Treaty Duty

“Due regard” is a treaty obligation. It is not a discretionary policy preference. The obligation is fact-specific. It requires the acting State to account for the nature and importance of the other State’s rights, the anticipated impairment, the importance of the planned activity, and the availability of alternatives or adjustments that reduce friction. This formulation rejects two common overstatements. First, due regard is not a coastal-State unilateral power to block lawful navigation, overflight, or related operational uses. Second, due regard is not satisfied by minimal awareness when impairment is foreseeable, and practicable mitigation exists.^{7 8}

For commanders and operators, due regard is implemented through disciplined planning and execution. The practical test is whether the operation can be explained, on the record, as (a) a legitimate exercise of the Convention’s preserved EEZ freedoms, (b) conducted with reasonable measures to avoid or minimize unreasonable impairment of coastal-State EEZ rights, and (c) adjusted where feasible to reduce friction without surrendering the underlying lawful use. The stronger the expected impact on coastal-State resource activities or protected jurisdictional interests, the stronger the due-regard measures must be.⁹

3. The “Peaceful Purposes” Constraint: Charter-Consistent Conduct

UNCLOS applies the Convention’s peaceful-use obligations to EEZ operations by carrying forward relevant high-seas duties into the zone. Those obligations require States, in exercising their rights and performing their duties under UNCLOS, to refrain from any threat or use of force inconsistent with the U.N. Charter. This is a treaty constraint that imports a Charter baseline into maritime operations. It is not a free-standing rule that bans all military activity in the EEZ as such. The more defensible doctrinal posture is narrower and operational: the EEZ is not a sanctuary from military presence, but it is a zone in which presence and conduct must remain Charter-consistent and must not be executed as a threat or use of force.¹⁰

The Charter baseline is the controlling legal floor. The peaceful-use posture is also applied in practice through disciplined restraint in encounter management, because conduct that predictably increases escalation risk can carry threat-like meaning even when weapons are not employed. Operational legality is defended most credibly when a unit’s maneuvering, posture, and communications remain clearly consistent with professional safety norms and non-compulsive intent.^{11 12}

State practice is not uniform on the permissible scope of certain military and intelligence activities in the EEZ. Some coastal States assert that specific activities require consent, prior notification, or additional constraints beyond due regard, while many maritime user States treat those activities as permitted when they are tied to navigation and overflight and are executed with due regard and Charter-consistent conduct. The operational implication is predictable: contested legal positions increase the likelihood of challenges, shadowing, and protests, and they increase the premium on documentation, communications discipline, and avoidable-risk control.¹³

This matters because peaceful-use analysis is conduct-driven. Unsafe close approaches, deliberate obstruction intended to compel changes in course or speed, or attack-like cues can convert an otherwise lawful presence into conduct that is harder to defend as Charter-consistent, depending on the circumstances and signaling. These are illustrative patterns, not allegations about any specific incident.¹⁴

4. Implementing Conventions: Evidence of Due Regard

Treaty obligations under UNCLOS are distinct from implementing safety conventions, but the conventions matter operationally because compliance supports due regard and reduces escalation risk. The COLREGs provide binding navigation rules intended to prevent collisions and require prudent seamanship, including special regard for the circumstances and dangers of navigation. Warships are not carved out of COLREG applicability by status alone, and disciplined COLREG compliance is a practical due-regard measure during encounters.¹⁵

SOLAS and related IMO instruments establish standards for the safety of navigation and ship operation. SOLAS Chapter V expressly excludes warships, naval auxiliaries, and other government non-commercial vessels, while encouraging them to act consistently so far as reasonable and practicable. Even where SOLAS does not formally apply to a warship, its navigational standards remain relevant as professional benchmarks and as evidence of reasonable precautions. Where operations generate navigational risk, such as dense traffic, night operations, flight/ship interaction, the safety-convention baseline provides the commander with defensible measures that align with due regard and reduce the chance that a navigational incident becomes a legal dispute.^{16 17}

Operationally, disciplined seamanship and clear documentation are the most defensible ways to demonstrate that due regard was applied in implementing UNCLOS obligations in the EEZ.¹⁸

5. Case Illustrations: What Tribunals Have Treated as Legally Significant

International decisions underline that due regard is a real constraint on operational content. In the South China Sea Arbitration, the Tribunal treated the Convention’s EEZ due regard duty as a meaningful obligation in relation to activities affecting another State’s EEZ rights, and it endorsed the view that the extent of regard depends on the rights at stake, anticipated impairment, activity importance, and available alternatives. The Tribunal expressly drew on the Chagos Marine Protected Area Arbitration’s due-regard formulation, which rejected any single universal rule and instead required circumstance-based balancing.^{19 20}

The South China Sea Arbitration also addressed the relationship between due regard and State responsibility for the conduct of vessels and other actors in certain contexts. It relied on the ITLOS SRFC Advisory Opinion to describe due diligence as the relevant standard for a State’s obligation to take necessary measures to ensure its nationals and vessels do not engage in unlawful conduct affecting another State’s EEZ rights. The operational takeaway is narrow and commander-relevant: when an operation foreseeably affects another State’s EEZ rights, the acting State’s duty is measured by whether it took reasonable, practicable measures to prevent unlawful impairment and manage risk.^{21 22}

Conclusion

UNCLOS permits foreign navigation, overflight, and related operational uses in the EEZ. Still, it conditions that permissive space through two binding constraints: due regard to the coastal State’s EEZ rights and duties, and Charter-consistent peaceful-use conduct. Coastal-State enforcement authority in the EEZ is subject-matter specific but operationally consequential, particularly in living resources, pollution-control contexts, and marine scientific research. Due regard is a treaty duty of fact-specific balancing. It is not a coastal-State unilateral power to block lawful use, and it is not satisfied by minimal awareness when impairment is foreseeable. The peaceful-use constraint does not demilitarize the EEZ; it constrains behavior by prohibiting threat or use of force and by reinforcing disciplined, non-coercive execution and signaling control. Commanders and operators reduce legal exposure by building an explicit due-regard record—identifying coastal-State rights engaged, minimizing impairment where practicable, and maintaining disciplined execution, communications, and documentation suitable for later legal review.^{23 24 25}

Footnotes:

1. United Nations Convention on the Law of the Sea art. 58(1-3), Dec. 10, 1982, 1833 U.N.T.S. 3 [hereinafter UNCLOS]. ↩︎
2. Charter of the United Nations art. 2, ¶ 4, June 26, 1945, 1 U.N.T.S. XVI [hereinafter U.N. Charter] ↩︎
3. UNCLOS art. 56(1), 58(1), 58(3). ↩︎
4. Id. arts. 2–3, 55–58. ↩︎
5. Vienna Convention on the Law of Treaties art. 31(1), May 23, 1969, 1155 U.N.T.S. 331. ↩︎
6. UNCLOS arts. 73, 220, 246. ↩︎
7. Id. art. 58(1)–(3). ↩︎
8. Chagos Marine Protected Area Arbitration (Mauritius v. U.K.), PCA Case No. 2011-03, Award, ¶ 519 (Mar. 18, 2015) [hereinafter Chagos MPA Award]. ↩︎
9. Chagos MPA Award, ¶ 519; UNCLOS art. 58(3). ↩︎
10. UNCLOS arts. 58(1)–(2), 87(1), 88, 301; U.N. Charter art. 2, ¶ 4. ↩︎
11. UNCLOS arts. 58(2), 301; U.N. Charter art. 2, ¶ 4. ↩︎
12. Convention on the International Regulations for Preventing Collisions at Sea, Rules 1(a), 2, 7–8, Oct. 20, 1972, 1050 U.N.T.S. 16 [hereinafter COLREG]. ↩︎
13. UNCLOS arts. 58(1)–(2), 87(1), 301; U.N. Charter art. 2, ¶ 4. ↩︎
14. U.N. Charter art. 2, ¶ 4. UNCLOS arts. 56(1), 58(3), 301. ↩︎
15. UNCLOS. art. 58(3); COLREG, Rules 1(a), 2, 7–8. ↩︎
16. International Convention for the Safety of Life at Sea ch. V, regs. 1(1), 34, Nov. 1, 1974, 1184 U.N.T.S. 278 [hereinafter SOLAS]. ↩︎
17. COLREG, Rules 1(a), 2, 7–8; SOLAS ch. V, reg. 34. ↩︎
18. UNCLOS art. 58(3). ↩︎
19. The South China Sea Arbitration (Phil. v. China), PCA Case No. 2013-19, Award, ¶¶ 741–44 (July 12, 2016) [hereinafter South China Sea Award]. ↩︎
20. Chagos MPA Award, ¶ 519. ↩︎
21. Sub-Regional Fisheries Commission (SRFC) Advisory Opinion, ¶¶ 124, 129 (Int’l Trib. L. Sea Apr. 2, 2015), 2015 ITLOS Rep. 4. South China Sea Award, ¶ 743 ↩︎
22. UNCLOS art. 58(3). ↩︎
23. Id. arts. 58(1)–(3), 88, 301. ↩︎
24. Chagos MPA Award, ¶ 519; South China Sea Award, ¶¶ 741–44. ↩︎
25. UNCLOS arts. 58(2), 301; U.N. Charter art. 2, ¶ 4. ↩︎