People v. Foster
Supreme Court of Illinois
457 N.E.2d 405 (1983)
James Foster (defendant) approached John Ragsdale to enlist his help robbing an elderly man, but Ragsdale, upon realizing Foster was serious, strung him along to gather information before reporting the plan to police, leading to Foster's arrest when he and Ragsdale met at the planned robbery scene; a jury convicted Foster of conspiracy to commit robbery, but an intermediate appellate court reversed, applying the bilateral theory of conspiracy (requiring an actual agreement between two genuine parties) since Ragsdale had only pretended to agree. The state appealed, arguing Illinois's 1961 statutory amendment adopted the unilateral theory (requiring only one party's genuine intent to agree) or, alternatively, that sufficient evidence existed even under the bilateral theory.
Whether a state's conspiracy statute, amended to describe conspiracy in terms of a single person's agreement to commit a crime, adopted the unilateral theory of conspiracy allowing conviction even when the only other party merely feigned agreement.