In Grunewald, the United States Supreme Court concluded that prosecutors cannot “extend the life of a conspiracy indefinitely” by inferring a conspiracy to conceal “from mere overt acts of concealment.” 353 U.S. at 402. Specifically, the Supreme Court held that after the central criminal purposes of a conspiracy have been attained, a subsidiary conspiracy to conceal may not be implied from circumstantial evidence showing merely that the conspiracy was kept a secret and that the conspirators took care to cover up their crime in order to escape detection and punishment.
The Supreme Court stressed a “vital distinction” “between acts of concealment done in furtherance of the main criminal objectives of the conspiracy,” which extend the conspiracy and toll the statute of limitations, and “acts of concealment done after these central objectives have been attained, for the purpose only of covering up after the crime.” Id. at 405. In Grunewald, the Supreme Court ultimately reversed the defendants’ convictions for conspiracy to defraud the United States because the Government failed to “show anything like an express original agreement among the conspirators to continue to act in concert in order to cover up, for their own self-protection, traces of the crime after its commission.” Id. at 404, 424.
The “vital distinction” between acts of concealment done in furtherance of the main criminal objectives of the conspiracy” and “acts of concealment done after these central objectives have been attained is a necessary one. Otherwise, the prosecution would almost always be able to undermine a statute of limitations by pointing to the fact that the accused kept their alleged criminal acts a secret.