The United States government (plaintiff) prosecuted Erick Arias Campos (defendant) for illegal possession with intent to distribute methamphetamine. The federal district court trial evidence showed that police officers found methamphetamine in Campos's room, along with a gun, ammunition, and false identification. A typical amount of methamphetamine for personal consumption was 3.5 grams, worth about $70. The officers found 50.6 grams in Campos's room. This was enough to qualify as a distribution amount worth between $1,000 and $1,500. A drug dealer could afford that amount, but not a poorly paid day-worker like Campos, unless he had an illegal source of income. Downstairs, the officers found a pen casing that contained methamphetamine residue. The officers testified that Campos exhibited no signs of drug addiction and had no drug paraphernalia on his person. Campos testified that he was a methamphetamine addict who used the pen casing to ingest the drug, and that he only had a large supply of methamphetamine on hand because he bought it at the bargain price of only $200. A witness for Campos testified that he saw Campos line up small amounts of methamphetamine for ingestion, though the witness admitted that he never actually saw Campos ingest the drugs. The jury convicted Campos, and he moved for a new trial. The judge found the defense testimony as to Campos's drug addiction credible, especially in light of the methamphetamine-tainted pen. The judge ruled that the government's circumstantial evidence against Campos was not strong enough to prove beyond a reasonable doubt that Campos intended to distribute methamphetamine, and that this suggested that the jury's verdict indicated a possible miscarriage of justice that entitled Campos to a new trial. The government appealed the judge's ruling to the United States Court of Appeals for the Eighth Circuit.