The legal regime of 'right of innocent passage' is a cornerstone of the law of the sea, balancing the sovereignty of coastal states with the freedom of navigation for all nations. This right is primarily codified in the 1982 United Nations Convention on the Law of the Sea (UNCLOS).

1. Territorial Waters and Sovereignty:

• Every coastal state has sovereignty over its territorial sea, which extends up to 12 nautical miles from its baselines (Article 3, UNCLOS). This sovereignty extends to the airspace above, the seabed below, and the subsoil thereof.
• However, this sovereignty is not absolute; it is subject to the right of innocent passage for foreign vessels.

2. Right of Innocent Passage (UNCLOS Part II, Section 3, Articles 17-26):

• Definition (Article 17): Ships of all States, whether coastal or land-locked, enjoy the right of innocent passage through the territorial sea.
• Meaning of Passage (Article 18): Passage means navigation through the territorial sea for the purpose of:
  • Traversing that sea without entering internal waters or calling at a roadstead or port facility outside internal waters.
  • Proceeding to or from internal waters or a call at such roadstead or port facility.
  • Passage must be continuous and expeditious. Stopping and anchoring are permitted only if incidental to ordinary navigation or rendered necessary by force majeure (unforeseeable circumstances) or distress, or for rendering assistance to persons, ships, or aircraft in danger.
• Meaning of Innocent (Article 19): Passage is innocent so long as it is not prejudicial to the peace, good order, or security of the coastal State. It is deemed prejudicial if a foreign ship engages in any of the following activities in the territorial sea:
  • Any threat or use of force against the sovereignty, territorial integrity, or political independence of the coastal State.
  • Any exercise or practice with weapons of any kind.
  • Any act aimed at collecting information to the prejudice of the defence or security of the coastal State.
  • Any act of propaganda aimed at affecting the defence or security of the coastal State.
  • The launching, landing, or taking on board of any aircraft or military device.
  • The loading or unloading of any commodity, currency, or person contrary to the customs, fiscal, immigration, or sanitary laws of the coastal State.
  • Any act of willful and serious pollution.
  • Any fishing activities.
  • The carrying out of research or survey activities.
  • Any act aimed at interfering with any systems of communication or any other facilities or installations of the coastal State.
  • Any other activity not having a direct bearing on passage.
• Submarines (Article 20): Submarines and other underwater vehicles are required to navigate on the surface and show their flag during innocent passage.
• Coastal State Rights and Duties (Articles 21-26):
  • Coastal states can adopt laws and regulations relating to innocent passage, provided they are in conformity with UNCLOS and do not hamper innocent passage.
  • They can take necessary steps in their territorial sea to prevent passage that is not innocent.
  • They cannot levy charges upon foreign ships for mere passage.
  • They must give due publicity to any danger to navigation of which they have knowledge within their territorial sea.
  • Coastal states may temporarily suspend innocent passage in specified areas of their territorial sea if such suspension is essential for the protection of its security, provided it is duly published.

3. International Straits (UNCLOS Part III, Articles 34-45):

• International straits are defined as those used for international navigation between one part of the high seas or an exclusive economic zone (EEZ) and another part of the high seas or an EEZ.
• For such straits, a special, more robust regime of 'transit passage' applies, rather than simple innocent passage.
• Transit Passage (Article 38):
  • Definition: Transit passage means the exercise of the freedom of navigation and overflight solely for the purpose of continuous and expeditious transit of the strait.
  • Key Differences from Innocent Passage:
    • Non-suspendable: The right of transit passage cannot be suspended by the coastal state, unlike innocent passage.
    • Submarines: Submarines are allowed to proceed submerged during transit passage (Article 38(2)).
    • Overflight: Aircraft also enjoy the right of overflight, which is not part of innocent passage.
    • Less Coastal State Control: Coastal states have fewer rights to regulate transit passage compared to innocent passage. They can adopt laws relating to safety of navigation, pollution, fishing, and customs/fiscal/immigration/sanitary laws, but these must not hamper transit passage.
• Exceptions: The regime of transit passage does not apply to straits where a high seas route or an EEZ route of similar convenience exists seaward of the strait (Article 38(1)). In such cases, the regime of innocent passage applies.
• Archipelagic Sea Lanes Passage (Articles 53-54): A similar, but distinct, regime applies to archipelagic sea lanes through archipelagic waters, granting a right of passage for ships and aircraft.

In essence, the right of innocent passage through territorial waters is a limited right, subject to strict conditions to protect the coastal state's security and interests. However, for international straits, the more expansive right of transit passage ensures unimpeded navigation and overflight, reflecting the global interest in maintaining open channels for international commerce and communication.