Jean-Baptiste Say (] ; 5 January 1767 – 15 November 1832) was a French economist and businessman.
 He had classically liberal views and argued in favor of competition, free trade, and lifting restraints on business.
 He is best known for Say's Law, also known as the law of markets, which he popularized.
 Scholars disagree on the surprisingly subtle question of whether it was Say who first stated what we now call Say's Law.
Andrea Grubb Barthwell, M.D. (born 1953 or 1954) worked in the White House under President of the United States George W. Bush as Deputy Director for Demand Reduction at the Office of National Drug Control Policy.
Demand reduction refers to efforts aimed at reducing the public desire for illegal and illicit drugs.
 The drug policy is in contrast to the reduction of drug supply, but the two policies are often implemented together.
 Some discussions of demand reduction make a distinction between policies that address single issues (such as public "knowledge-of-harms") or are short-term interventions (such as in-school programs), and those that approach drug demand as a complex issue with multiple social risk factors.
 Some economists such as Milton Friedman argue that due to the law of supply and demand, reducing demand is the only effective way to reduce drug use long-term.
 It is questionable, however, whether demand reduction programs actually reduce demand.
Sir Ian Charles Rayner Byatt (born 11 March 1935) is a British economist who was the Director General of the economic regulator of the water industry in England and Wales, Ofwat, from its creation at the time of the privatization of the water industry in 1989 until 2000.
 During his tenure he was responsible for a substantial price reduction imposed on private water companies in 1999 that sent the stocks of these companies tumbling down.
 He then joined the newly created economic consulting firm Frontier Economics.
 From 2005–11 he was the Chairman of the Water Industry Commission for Scotland, the economic regulator of the Scottish water industry.
 In 2012 he criticized the Thames Tideway Scheme as unnecessary and argued that private firms should not receive the massive subsidies they have requested to finance the scheme.
Herbert D. Kleber, M.D., is an American psychiatrist and substance abuse researcher.
 From 1968 to 1989, he founded and headed the Drug Dependence Unit at Yale University, where he was Professor of Psychiatry.
 He then served for 2½ years as the Deputy Director for Demand Reduction at the Office of National Drug Control Policy in the White House.
A drug policy is the policy, usually of a government, regarding the control and regulation of drugs considered dangerous, particularly those which are addictive.
 Governments try to combat drug addiction with policies which address both the demand and supply of drugs, as well as policies which can mitigate the harms of drug abuse, and for medical treatment.
 Demand reduction measures include prohibition, fines for drug offenses, incarceration for persons convicted for drug offenses, treatment (such as voluntary rehabilitation, coercive care, or supply on medical prescription for drug abusers), awareness campaigns, community social services, and support for families.
 Supply side reduction involves measures such as enacting foreign policy aimed at eradicating the international cultivation of plants used to make drugs and interception of drug trafficking.
 Policies which may help mitigate the effects of drug abuse include needle exchange and drug substitution programs, as well as free facilities for testing a drug's purity.
Global Centurion is a non-profit organization that works to combat modern slavery by focusing on demand.
 To date, efforts to combat human trafficking have focused on rescue and restoration of victims, and prosecution of traffickers.
 Few efforts focus on the buyers – those that fuel the market for human trafficking – whether its sex, labor or organ trafficking.
 Global Centurion believes that in order to combat human trafficking, a comprehensive approach is required, one that recognizes the "slavery triangle:" the supply (victims), demand ("buyers"), and distribution (traffickers).
 Global Centurion addresses the demand side by in three ways: 1) Research on demand reduction and related issues; 2) training and awareness programs targeting demand; and 3) partnerships and collaboration.
 A key project is the creation of an international modern slavery case law database, with over 6,000 cases from around the world.
Milton Friedman ( ; July 31, 1912 – November 16, 2006) was an American economist who received the 1976 Nobel Memorial Prize in Economic Sciences for his research on consumption analysis, monetary history and theory, and the complexity of stabilization policy.
 With George Stigler and others, Friedman was among the intellectual leaders of the second generation of Chicago price theory, a methodological movement at the University of Chicago's Department of Economics, Law School, and Graduate School of Business from the 1940s onward.
 Several students and young professors that were recruited or mentored by Friedman at Chicago went on to become leading economists; they include Gary Becker, Robert Fogel, Thomas Sowell, and Robert Lucas, Jr.
Supply reduction is one approach to social problems such as drug addiction.
 Other approaches are demand reduction and harm reduction.
Cindy Fazey is a criminologist and former Chief of Demand Reduction for the United Nations Drug Control Programme.
 She has been Professor of International Drug Policy at the University of Liverpool since 1998.
 Fazey has spoken in the past of "the complete failure of national and international drugs policies."
 She has also noted that the organization of the international drug control apparatus makes it difficult to reform the system.
 On 24 February 2004, Fazey gave a speech at the Perspective on Cannabis conference at Liverpool titled "Can you hear the grass growing?
 Cannabis and the repatriation of drug policy".

Question: Which economist from University of Chicago argued in favor of demand reduction? 
Answer: Milton Friedman