Who has to provide evidence?

When we watch a black and white movie, most of the scene is actually filled with different tones of grey. We can not have it just in pure black and white. Similarly, there are often ‘grey’ areas of debate in matters relating to adopting a fishery management measures. In the court of justice in most developed states, the prosecuted is considered to be innocent, until the prosecutor proves that he is guilty with convincing evidences. The responsibility of providing evidence is on the prosecutor. On the other hand, there is other type of principle in which the prosecuted is considered guilty, until he proves himself innocent. (Criminal Procedure in Napoleon Code).
Very often, we face a similar situation to such criminal procedures, where we have to make a clear judgment and decision. When it comes to the risk management, the Napoleon code tends to be applied. i.e. until safety is confirmed, they should be considered as dangerous. Then, does 100% safety need to be confirmed, or is 80% or 60% acceptable? The problem is where the line can be drawn for making such decisions.
Since the principle of precautionary approach has been adopted in fishery management, the decision-making
process is often very controversial, as the interpretation of this approach differs among people. I have had several experiences relating to this subject, and I can not forget the extreme case I had in one RFMO Scientific Committee, a few years ago.
At the floor, all of a sudden, it was proposed that all longliners must take seabirds mitigation measures in an entire Ocean. It was common knowledge that the interaction between tuna longline fishing and seabirds occur mostly in high latitude areas. So I argued that there was no reason to expand such measures to the entire ocean, where no seabirds by-catch occurs. The group who proposed this measure insisted that there had been no report showing there is no by-catch occurred in past in the low latitude areas and hence the mitigation measures have to be applied to all the areas. I further argued that a sudden introduction of such measures would require a great cost and sacrifice in labor for fishers: without any evidence to show such interaction exists, we cannot convince fishers to accept such decision, particularly since the fishers know through experience that they would not by-catch seabirds in most of their fishing grounds. Unfortunately, the majority agreed that until evidence is given that seabirds are not captured by the longline in the tropical waters, they should take precautionary mitigation measures.
At the Commission meeting, however, this extreme recommendation was not adopted and in a couple of years,
Japanese scientists gathered enough information to prove that there has been no seabird by-catch in the area under question. This is an example of a twisted application of the precautionary approach for the managements. Currently, so-called hot spots (by-catch area) have been identified and mitigation measures are introduced only to those areas.
In future, such an unexpected sudden attack to the fisheries might increase. The problem is whether the fishers have to prove all the time that they are innocent in all these problems, or such a proposal should come on the basis that fishers are guilty. The difficulty is that suspicions can be raised very easily, often based on rumor, whilst proving evidence for innocence is very difficult, even more than proving evidence for guilty. The precautionary approach should not be applied only on a baseless suspicion but instead, should be through a risk analysis based on certain evidences of guilty and/or innocent. Furthermore, even with the risk analyses, 100% probability of either side would be very rare. Therefore the decision should not be made on 100% probability but on a certain acceptable limit in the probability of risk. Besides, we should remember that those measures can be always re-analyzed and changed depending on the new situation and/or evidences.