I had an SCD expert look into this, here's her response:
I have kept looking and still can't find information to say it is either legal or illegal. Which may mean that research to determine SCD legality has not been done.
If you decide to use it anyway there is some interesting information at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3506936/
Also it may be better as an extract if there are any properties in the root that would make it SCD illegal.
And also please note that some research indicates it may affect (lower) blood pressure and/or blood sugar. So, there may be contraindications depending on a person health issues or if they are taking medications. You can also discuss with a pharmacist an/or health care provider for insight on drug interactions or health implications.