"There is shared concern among researchers that adding these substances to Schedule I could hinder medical research. As previously mentioned, Professor Huffman did not intend for K2 to be consumed by humans. He is, however, against adding synthetic cannabinoids to Schedule I, asserting that there is still much to learn about synthetic cannabinoids and that placing them on Schedule I would create too many hurdles for researchers who need to access these drugs.58 Professor Huffman has created several synthetic cannabinoids that are seen as showing promise in treating skin cancers, pain, and inflammation."

Source

Sacco, Lisa N. and Finklea, Kristin M., "Synthetic Drugs: Overview and Issues for Congress," Congressional Research Service (Washington, DC: Library of Congress, October 28, 2011), p. 13.