Until relatively recently (1980s), scientists believed that CBD was a natural precursor to the formation of THC, and since THC was a strictly controlled substance back then (it still is), it only followed that CBD should be equally strictly regulated. However, CBD is actually unrelated to the chemical chain that results in THC. They share some characteristics but are created via different paths. Again, unlike THC, CBD is considered a legal cannabinoid and is safe to consume in any amount and concentration.
^ Jump up to: a b c Campos AC, Moreira FA, Gomes FV, Del Bel EA, Guimarães FS (December 2012). "Multiple mechanisms involved in the large-spectrum therapeutic potential of cannabidiol in psychiatric disorders". Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences (Review). 367 (1607): 3364–78. doi:10.1098/rstb.2011.0389. PMC 3481531. PMID 23108553.