To simplify, perhaps too, far, what we've learned about the various options for legal structures so far:
1. The USA's constitution is driven by the States through their representation in the Senate and the House. Federal authorities cannot change the constitution on their own. That means that even presidential orders are possible only within the confines of those matters that are specifically federal and that the Federal Court has authority in relation to federal matters, not to those which are reserved to the States.

2. The EU's model provides for the States to be subject to the Federal Parliament which has limited powers. This is done through Directives. While States have some power to reject Directives, they are rarely used. Instead, States pass such laws as they want while paying lip service to the EU's Directives. The EU rarely takes action against states which do this. It is rarely noted that amongst the states that most closely followed EU Directives was the UK while its competitors often went as far as they could to "interpret" them. This was possible because Directives are addressed to states, not to persons within them. The EU has now adopted the system of "Regulations." This is similar, in concept, to the UK's Statutory Instruments: primary law empowers the executive (subject to certain controls) to make law under "enabling provisions." This means that in relation to areas of law where the EU has a global policy, individuals and companies within countries are directly subject to EU law. The test case for this was financial regulation through the European Central Bank and now the EU is creating a new "Anti-Money Laundering Authority" which will directly supervise businesses that are regulated for certain financial crime purposes.

In ASEAN, there is no federal authority on either the USA's or the EU's model. There is no "Common Law". There are treaties, memoranda of understanding and other inter-state agreements. There is general agreement but no common legislative approach in relation to drugs or money laundering other than that which comes from the Financial Action Task Force and the Asia Pacific Group. Within the constraints imposed by those two groups, individual countries are free to make such drugs and money laundering laws as they think fit. There are many influences - the UNODC, the IMF, The Asian Development Bank and more but they are just that: influential.

So banks etc. operating across the region have to reconcile multiple laws and regulations. And, as is becoming increasingly apparent, there are multiple views within the region and, even, within countries.

For example, Malaysia is having a discussion about medical marijuana. Ministers and civil servants are openly talking about the degree of liberalisation and legalisation and when. And the debate is not centred solely on the desirability or otherwise of weed: it's now an economic debate. This week, Indonesia's highest court ruled that a ban on medical marijuana was not in breach of the constitution. Part of the reasoning in many countries is that drugs are haram under Islam. Yet, in Indonesia, the primary area for cultivation - and it produces a lot - is the hard-line Islamist area of Aceh. As Vice reported in 2019 - a decade-long effort by the central government to reduce the trade has not worked. Aceh has strict Islamic laws - even going so far as to punish women for riding a motorcycle - but it is, on other bases, a lawless place. It is, for example, the principle base for pirates in the region. And it's only a relatively short marine hop to both Myanmar and Thailand. The argument that cannabis is an effective cash crop is amply demonstrated. So the national government, albeit quietly, has begun to question whether the national economy could benefit, just as was argued in Thailand. In Malaysia, the argument has, so far, not been much about profit but more about the effects. Only this week, a Minister has said that there should be a distinction drawn between medical MJ and those products with high THC. He has reminded people that all cannabis use, of all types, is illegal in Malaysia. But with Thailand having made the decision and Indonesia apparently moving towards it, Malaysia is likely to find itself a hold-out while stocks are freely available metres from its borders.

But for now, Thailand stands alone in the region and that means that dealing with Thai banks and even businesses requires risk assessment.

Which brings me back to the start, sitting in the café in Singapore, surrounded by Thai products. It reminded me that some years ago one of my favourite snacks was a tin of own-label curried tuna from a Singapore supermarket. And that reminded me that, before marijuana was viewed as a universally bad thing, Thai cuisine often included it.

How easy it would be to produce canned food with weed in it and to sell it across the world as a product legally produced in its home country? And how difficult to identify (unless someone listed it as an ingredient) at borders. That, of itself, isn't the real problem. The real problem is that, in doing it, the entire supply chain for canned foodstuffs would be subject to suspicion.

And so would all traders who export or import such items. This would not be old style smuggling of hiding a bag of something in a shampoo bottle but a product actually integrated with the drug so it's not identifiable by any mechanical or electronic scanning.

The questions raised by Thailand's decisions are far greater than the obvious but it is the obvious that is the most troubling.

And here we have to fall back onto general principles and, in each case, to look at national law.

If a person grows, processes and sells in Thailand, he commits no offence.
If he uses that money to buy goods or services overseas, or even places his deposits in a bank, he commits no offence UNLESS the bank's local law is contrary to the usual "commonality of offence" provisions.
It is that point that requires banks in each jurisdiction to check their own law.
It is also that point that regulators might decide, on instruction from governments, to issue regulations for. They may say that the bank commits a regulatory (not criminal) offence if it takes in money from the legal production of drugs in another jurisdiction.

That may be the greater threat for the simple reason that governments that are themselves discussing liberalisation if not legalisation of at least some cannabis products would find themselves in a difficult position if they tried to change counter-money laundering laws relating to commonality of offence - how would it affect regional relationships?

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