Krulewitch v. United States

Krulewitch (defendant) and another person were charged with conspiring to violate, and actually violating, the Mann Act by transporting a woman across state lines for prostitution. At trial, the government argued the conspiracy continued even after the transportation itself was completed, which mattered because statements made by any conspirator during an ongoing conspiracy are admissible as evidence against all co-conspirators despite normally being excluded as hearsay. The Supreme Court granted certiorari to review whether the conspiracy had, in fact, continued.