D was invited by Luke Rinderknecht to join an ongoing enterprise distributing a controlled substance popularly known as “ecstasy.” D delivered ecstasy pills, which he received from Rinderknecht to other conspirators, who then sold them to consumers. He netted over $30,000. A few months after joining, D advised Rinderknecht and other co-conspirators that he was withdrawing from the conspiracy. He has not sold illegal drugs of any kind since. He has not used any illegal drugs since graduating from college. When approached by federal law enforcement agents, D admitted his limited participation in the distribution of ecstasy, and the agents took no further action at that time. On April 28, 2004-approximately a year and a half after this initial interview, and three and a half years after D withdrew from the conspiracy-an indictment was returned. D moved back to Iowa and surrendered to the authorities. While free on his own recognizance, D started his own business in the construction industry and made over $2,000 per month in profits. D entered into a plea agreement which stated that D had communicated his intent to stop distributing ecstasy to Rinderknecht and other members of the conspiracy. The agreement further provided that recent changes in the Guidelines that enhanced the recommended punishment for distributing ecstasy were not applicable to Gall because he had withdrawn from the conspiracy prior to the effective date of those changes. The PSR stated that D had not provided new information to the agents. It recommended a sentencing range of 30 to 37 months of imprisonment. At the hearing, D’s parents and other relatives, his fiancé, neighbors, and representatives of firms doing business with him, uniformly praising his character and work ethic. P urged that “the Guidelines are appropriate and should be followed,” and requested that the court impose a prison sentence within the Guidelines range. D’s co-conspirators had been sentenced to 30 and 35 months, respectively, but upon further questioning by the District Court, he acknowledged that neither of them had voluntarily withdrawn from the conspiracy. D got probation for a term of 36 months. The judge cited D's explicit withdrawal from the conspiracy almost four years before the filing of the Indictment, D’s post-offense conduct, especially obtaining a college degree and the start of his own successful business, the support of family and friends, lack of criminal history, and his age at the time of the offense conduct, all warrant the sentence imposed, which was sufficient, but not greater than necessary to serve the purposes of sentencing. The Court of Appeals reversed and remanded for resentencing. A sentence outside of the Guidelines range must be supported by a justification that “ ‘ “is proportional to the extent of the difference between the advisory range and the sentence imposed.” D's sentence amounted to “a 100% downward variance,” and such a variance must be supported by extraordinary circumstances. The Supreme Court granted certiorari.