Book page 68-71

ENFORCEMENT OF POLLUTION LAWS 
APPLICABLE TO VESSELS
Section: Part XII, Articles 192-237   

General  Enforcement Concept	Port State Enforcement	Coastal State Enforcement

 ARTICLES 217-233

The provisions of enforcement are carefully designed to balance the opposing interests of the flag states and the coastal states. Just as the flag state has primary legislative jurisdiction over its vessels, it also bears the primary responsibility for ensuring that its vessels comply with international law.[1] In the event of a violation, the flag state is to institute investigations and proceedings.[2] Penalties provided by the laws and regulations of the flag state must be sufficiently severe to discourage violations, wherever they might occur. [3]Although official vessels are not subject to these Convention provisions, similar measures are to be implemented for such ships by each state,[4] which is also liable for any damage caused by its vessels.[5]

[1] Art. 217, Para . 1,    [2] Art. 217, Para . 4,      [3] Art. 217, Para . 8,     [4] Art. 236,     [5] Ibid.; Art. 31; 42; Para . 5; 235, 304,     [6] Art. 219-221,   [7] Art. 219; 220, (2)&(6),

[8] Art. 220, Para . 1,    [9] Art. 226, Subpara. 1(a),    [10] Art. 220(7); 226(1),    [11] Art. 292; 297(1)(c),   [12] Art. 223, 231,   [13] Art. 223,     [14] Art. 231,

[15] Art. 228,     [16] Art. 219,     [17] Art. 226, Subpara. 1(c); 231,     [18] Art. 232,     19] Art. 218, Para . 2-3,    [20] Art. 218, Para . 4

The coastal state, on the other hand, has been vested with rights (in varying degrees) to enforce pollution laws, although safeguards have been built in to ensure that this power can be exercised only to a limited extent. The measures, which can be taken,[6] depend on the exact nature of the violation with regard to two sets of factors: 

1) Location of violation: territorial sea, exclusive economic zone; location of vessel: territorial sea, exclusive economic zone, voluntarily in port 
2) Intensity of violation: substantial discharge, major damage, any violation; reasons for acting: warranted by evidence, clear grounds for believing.  

The measures the coastal state may take include request for information, physical inspection, proceedings, and even detention[7]. With some generalization, it can be said that the coastal state jurisdiction is strongest when the vessel is voluntarily in port[8] and weakens with increasing distance of the location of the violation from the coast (zone by zone) and the impact of the damage or the threat of damage.  

All measures must be taken in compliance with the safeguards given in Articles 223 to 233, which prohibit undue delay of a foreign vessel, excessive physical inspection, and general disregard for accepted international rules[9] and provide for the release of vessels, subject to reasonable procedures such as bonding or appropriate financial security.[10] If a detaining state has not released a vessel, the question is subject to compulsory dispute settlement.[11]

Finally, coastal states taking measures have obligations to other affected states, particularly the flag state,[12] and to international organizations.[13] The flag state must be notified of measures taken (although not in all circumstances), and all official reports concerning the measures must be submitted to the flag state.[14] The flag state can institute proceedings itself, thus suspending -with certain exceptions - the proceedings in the coastal state.[15] If a vessel has been detained, e.g., due to lack of seaworthiness,[16] the flag state must be informed promptly.[17]

States are liable for damages or loss resulting from such measures if the measures are unlawful or unreasonable.[18] This provision also applies to a port state, which investigates or institutes proceedings against a vessel based on an allegation of unlawful discharge on the high seas or in zones of other states (on request).[19]
Investigation reports are to be transmitted to the flag state or the coastal state upon request and instituted proceedings suspended.[20]