Annual export-import traffic in live-reef-fish commerce in Asia was confirmed not less than 25,000 tons caught using tons of cyanides. This was not included domestic consumption and deadfishes caused by cyanides. This condition clearly menaces the conversation of coral reef ecosystems and its related biota especially in Indonesia where utilization of 'potas' is growing. By environmental law set up since 1982, this kind of commerce is illegal. Legal matters on this issue became difficult to pursue because physical evidence required to determine whether an action or transaction was against the law or not oftenly difficult to prove. The police is usually faced with fish samples or other marine animals exposed to cyanides and to determine cyanide concentration, a sensitive, reliable and accurate method is needed even down to ppb level. The development of such method is urgently required for two reasons. First, the large and unique Indonesia must have handling system that is able to manage natural conservation process appropriately. Rapid sampling and analysis in the field as well as preparation of human resource in modern analytical proficiency are examples of the problems. Secondly, it may help law practitioners in providing them some scientific physical evidence for legal cases especially in marine environment protection. It is concluded that the role of marine analytical chemistry is very decisive in marine science development as well as in law enforcement.