The United States government (plaintiff) prosecuted Mathews (defendant) for accepting a bribe. Mathews was a Small Business Administration official in charge of providing aid to certain businesses. Mathews refused to aid one such business until the business's owner loaned him money. At the instigation of federal agents, the owner offered Mathews a bribe. Mathews accepted the bribe and the agents arrested him. At trial, Mathews claimed the agents entrapped him, and denied having acted with guilty intent. Because guilty intent was an element of the crime of accepting a bribe, the judge refused to instruct the jury on entrapment. The jury convicted Mathews. After an appellate court upheld Mathews's conviction, he appealed to the United States Supreme Court.