In Lev v. United States, the Supreme Court examined whether a defendant could be convicted of both conspiracy to commit an offense and the substantive offense itself under separate statutes. The case involved two individuals who were charged with conspiring to transport stolen goods across state lines and actually transporting those goods, in violation of two different sections of the same federal statute. They argued that they should not have been prosecuted for both offenses because they arose from a single act or transaction. The Supreme Court disagreed, holding that Congress intended to create distinct offenses when it enacted separate statutory provisions punishing conspiracy and the substantive crime itself. Therefore, prosecution for both crimes did not violate double jeopardy principles which prohibit multiple punishments for the same offense. This decision clarified that defendants can be punished separately for planning a crime (conspiracy) and carrying out that plan (the actual commission), even if these actions are part of one continuous sequence.

The dissenting opinion in the case of LEV v. UNITED STATES argued that the majority's decision was a departure from established legal principles and precedent. The dissent contended that the defendant should have been allowed to withdraw his guilty plea, as he had not been adequately informed of his rights at trial or during plea negotiations. It also asserted that it was improper for the court to accept a guilty plea without first ensuring that there was a factual basis for it, which is required by federal law. Furthermore, they believed this ruling could potentially undermine public confidence in the justice system by creating an appearance of unfairness and arbitrariness in criminal proceedings.