Complex sentence: In 1972, after volunteering with the National Organization for the Reform of Marijuana Laws, (NORML) Cowan wrote a cover article for Buckley's National Review, calling for Conservatives to support the legalization of marijuana, one of the first in a major opinion journal.
Split into simpler sentences: In 1972, after volunteering with the National Organization for the Reform of Marijuana Laws (NORML), Cowan wrote a cover article for Buckley's National Review. In it he called for Conservatives to support the legalization of marijuana, one of the first positions against prohibition in a major opinion journal.