The Bank Secrecy Act (“BSA”) implementing regulations at 31 CFR Chapter X require covered financial institutions to file reports of suspicious transactions with the Department of the Treasury’s Financial Crimes Enforcement Network (“FinCEN”) in circumstances where the bank knows, suspects, or has reason to suspect that the transaction “involves funds from illegal activities.”  The requirement to file such suspicious activity reports or “SARs” arises under federal law.  Marijuana-related business activity that has been legalized under certain state laws—e.g., recreational cannabis…