The claim that decriminalizing Marijuana would lead to increased use assumes
that prohibition is somewhat effective, in that it deters some from using the somewhat
readily available drug. (Claiming prohibition to be effective is different than claiming it
to be successful, which would necessitate an analysis of whether the benefits outweigh
the costs. It is not merely enough that consumption decreases, but that the decrease is
significant enough to warrant the hefty expenditures.) There are two main ways in which
criminalizing marijuana could decrease consumption. The first being that its illegality
increases price and consequently reduces demand. The second way in which prohibition
can decrease consumption is by fear of penalty for the consumer. Regardless of which of
these theories is the driving force, determining how effective prohibition is on reducing
consumption will provide a good idea of how use will adjust if marijuana is
decriminalized. Several studies have been conducted in an attempt to analyze the
effectiveness of both prohibition-caused reasons for refraining from marijuana use.