Complex sentence: Lee and Shlain argue that LSD influenced the social movements of the 1960s in the U.S. until the drug became illegal in 1966 and was listed as a Schedule I drug in 1970.
Split into simpler sentences: Lee and Shlain argue that LSD influenced the social movements of the 1960s. The drug became illegal in 1966 and was listed as a Schedule I drug in 1970.