Whether Illinois's 1961 conspiracy statute adopted a unilateral theory under which only the defendant must genuinely intend to agree to commit an offense.
Holding
No. Section 8-2(a) retained the bilateral theory of conspiracy and requires an actual agreement between at least two persons.
Reasoning
Before the 1961 revision, Illinois law plainly followed the traditional bilateral theory: the statute punished situations in which “two or more persons” conspired or agreed together. The revised statute instead said that “[a] person” commits conspiracy when, intending that an offense be committed, he agrees with another. The State argued that this change in wording showed an intent to require only one genuinely culpable participant.
The State's reading had some textual force, particularly because the Model Penal Code uses similar “a person” language and expressly embraces unilateral conspiracy. But the Model Penal Code commentary specifically explains that its drafters rejected the bilateral approach. Illinois's committee comments referred to the Model Penal Code yet never stated that Illinois was making the same major change. The Court found it unlikely that the drafters would silently make so profound a change in conspiracy law.
Decisions from other jurisdictions did not compel a unilateral reading. Although some courts treated comparable wording as a rejection of bilateral conspiracy, other courts interpreted statutes phrased in terms of “a person” to require a genuine agreement by at least two people. The split in authority weakened the State's claim that the revised language was unambiguous.
Illinois also separately criminalized solicitation, and solicitation covered virtually every situation that a unilateral-conspiracy theory would reach. Since solicitation and conspiracy carried substantially similar penalties, the Court saw little practical need to infer that the legislature had expanded conspiracy in that way without expressly saying so.
Section 8-2(b), which provides that conspiracy is not defeated because an alleged coconspirator was acquitted or lacked capacity to commit an offense, did not establish unilateral conspiracy. The committee comments showed that those provisions were designed to prevent inconsistent results arising from separate trials, different juries, and differing proof—not to eliminate the requirement of an actual agreement in the first instance. If the statute were unilateral, those provisions would have been unnecessary.
Two Illinois appellate decisions had already interpreted the amended statute as requiring bilateral conspiracy, and the legislature had not altered the statute after those decisions. Although legislative inaction is not conclusive, it supported the bilateral interpretation, especially because one decision had stood since 1975. Any remaining ambiguity in a criminal statute had to be resolved in the defendant's favor.