Shootinbud, I see no harm in the stuff either. And, I think it's pretty lame that something that has less toxins than probably a beer is illegal. That being said--I got this from the FDA website for your perusal. I think perhaps the lack of clear notices is probably indicative of a) more than just you and your dad goes to the woods to gather roots for tea b) I don't think it's a law that's really talked about, perhaps because it's another unpopular one c) with all the problems out there in the world--I really don't think law enforcement is going to have time to monitor all sassafras trees and the root usage of them 
 http://www.cfsan.fda.gov/~lrd/FCF189.html
http://www.cfsan.fda.gov/~lrd/FCF189.htmlTITLE 21--FOOD AND DRUGS 
CHAPTER I--FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN 
                          SERVICES (CONTINUED) 
PART 189--SUBSTANCES PROHIBITED FROM USE IN HUMAN FOOD--Table of Contents 
 Subpart B--Substances Generally Prohibited From Direct Addition or Use 
                              as Human Food 
Sec. 189.180  Safrole. 
    (a) Safrole is the chemical 4-allyl-1,2-methylenedioxy-benzene, 
C10H10O2. It is a natural constituent 
of the sassafras plant. Oil of sassafras is about 80 percent safrole. 
Isosafrole and dihydrosafrole are derivatives of safrole, and have been 
used as flavoring compounds.
    (b) Food containing any added safrole, oil of sassafras, isosafrole, 
or dihydrosafrole, as such, or food containing any safrole, oil of 
sassafras, isosafrole, or dihydrosafrole, e.g., sassafras bark, which is 
intended solely or primarily as a vehicle for imparting such substances 
to another food, e.g., sassafras tea, is deemed to be adulterated in 
violation of the act based upon an order published in the Federal 
Register of December 3, 1960 (25 FR 12412).
    (c) The analytical method used for detecting safrole, isosafrole and 
dihydrosafrole is in the "Journal of the Association of Official 
Analytical Chemists," Volume 54 (Number 4), pages 900 to 902, July 
1971, which is incorporated by reference. Copies are available from the 
Division of Food and Color Additives, Center for Food Safety and Applied 
Nutrition (HFS-200), Food and Drug Administration, 5100 Paint Branch 
Pkwy., College Park, MD 20740, or available for inspection at the Office 
of the Federal Register, 800 North Capitol Street, NW., suite 700, 
Washington, DC 20408. 
[42 FR 14659, Mar. 15, 1977, as amended at 42 FR 56729, Oct. 28, 1977; 
47 FR 11855, Mar. 19, 1982; 54 FR 24900, June 12, 1989]