7.1 General
While fines is commonly regarded as the main sanction to be used for non-compliance with MARPOL Annex VI, a brief review of other available enforcement measures is justified. Other forms of criminal sanctions, such as imprisonment, confiscation of the ship etc. are generally ruled out by the nature of the air emission violation, but also through the requirement in UNCLOS article 230 that "monetary penalties only may be imposed" with respect to pollution violations by foreign ships (the only exception being pollution in internal waters and 'wilful and serious' pollution in the territorial sea(1) Section 4.6 above. ). It appears from the negotiation history of the article that its main purpose is to avoid the use of prison sentences, hence leaving the door open for other types of (administrative) enforcement measures.(2) See UNCLOS Commentary Vol. IV, pp. 363-370. See also Ringbom note 45, p. 335 and Molenaar note 44, p. 237. In view of this, certain measures that could supplement or replace the penalties are briefly explored below.