In the case of Henderson, Correctional Superintendent v. Morgan in 1975, the U.S. Supreme Court ruled that a defendant could not be considered to have voluntarily and intelligently pleaded guilty if he was not aware of all elements of his crime at the time he entered his plea. The defendant, Willie James Morgan had been charged with first-degree murder but pleaded guilty to second-degree murder without being informed by either his counsel or the court about one essential element of this crime - intent to cause death. Later on appeal, it was found that there was no evidence showing that Morgan understood this requirement when pleading guilty; thus rendering his plea involuntary under due process clause as per Fourteenth Amendment. This decision emphasized on ensuring defendants' full understanding before accepting their pleas.

In the dissenting opinion for Henderson v. Morgan, Justice William H. Rehnquist argued that the majority's decision was based on an incorrect interpretation of Boykin v. Alabama and its requirements for a valid guilty plea. He contended that there is no constitutional requirement to explain every element of a crime to a defendant before accepting their guilty plea, as long as they understand the nature of the charges against them and voluntarily choose to plead guilty with competent legal advice. In this case, he believed that Morgan had received adequate counsel from his attorneys who advised him about pleading guilty to second-degree murder after originally being charged with first-degree murder. Furthermore, he pointed out that Morgan never claimed not understanding what he was doing when entering his plea nor did he ever try withdrawing it until years later which suggests satisfaction with his initial decision at least in some degree.