In the 1960 case of Bell et al. v. United States, the U.S Supreme Court ruled that when a defendant is convicted on multiple counts for different offenses arising from a single act or transaction, they cannot be sentenced separately for each offense. The defendants in this case were charged with and convicted of two separate crimes: robbing a bank and conspiring to rob it. Both charges stemmed from one act - the robbery itself - which led to their arrest and subsequent trial. They were given consecutive sentences for both convictions, effectively doubling their punishment time due to what was essentially one crime committed once against one victim (the bank). The court held that this constituted double jeopardy under the Fifth Amendment's protection against being tried twice for the same offense, hence reversing their conviction on conspiracy charge while upholding only on substantive count of bank robbery.

In the dissenting opinion for Bell et al. v. United States, Justice Hugo Black argued that the majority's interpretation of the Mann Act was overly broad and inconsistent with its original intent. He contended that Congress had intended to target commercialized vice, not private immoralities or indiscretions between consenting adults. Furthermore, he disagreed with the majority's view that transporting women across state lines for any "immoral purpose" constituted a violation of the Act regardless of whether it involved prostitution or other forms of debauchery as originally specified in legislative history. In his view, this expansive reading could potentially criminalize many types of behavior not contemplated by Congress when they passed this law such as couples cohabiting without being married who travel interstate together even if no money is exchanged nor exploitation occurred.