I'd be careful taking on a marijuana client at least from a Federal standpoint. Someone told me though the feds are considering legalizing it on their end. Thats just hearsay though. I have no stone cold facts.
Moral issues aside, the water is probably too muddy to be my cup of tea, cash business, potential accounting issues, availability of records, and various other compliance risks from the little that I understand.
I've heard its not so much of a moral issues as opposed to an insurance issue. Most banks and insurers will not or cannot deal with marijuana businesses. Now, what if you as the accountant has a marijuana client, your malpractice insurance could be negated.
Honestly, Im not sure I believe this but.......https://riskandinsurance.com/the-cannabis-contradiction/ <------safe. This could extend to accountants.