In the case of James Benjamin Puckett v. United States (2008), the U.S. Supreme Court ruled that a breach of plea agreement by the government is subject to harmless-error review, meaning it must be determined whether or not this error affected substantial rights and had an impact on the trial's outcome. Puckett was charged with armed bank robbery and agreed to plead guilty in exchange for certain concessions from prosecutors, including their recommendation for a reduced sentence due to acceptance of responsibility. However, after he committed another crime while awaiting sentencing, prosecutors argued against leniency at his sentencing hearing - effectively breaching their original agreement. The court held that although there was indeed a breach of plea agreement by the prosecution, Puckett failed to object at trial when he should have done so; therefore any potential harm caused by this error would need further examination before being considered grounds for overturning his conviction.

In the dissenting opinion for Puckett v. United States, Justice Souter argued that the majority's decision to apply a plain-error review was incorrect because it did not consider whether the error seriously affected "the fairness, integrity or public reputation of judicial proceedings." He believed that when a prosecutor breaks an agreement with no reasonable justification and gets away with it due to defense counsel’s oversight, this undermines confidence in plea bargaining process which is integral part of our criminal justice system. Furthermore, he pointed out that applying such stringent standard would discourage defendants from entering into plea agreements as they could not trust government to keep its end of bargain. This would lead to more trials and increased burden on already overburdened courts. Thus, according to him, even though defendant failed to object at trial court level about breach by prosecution; appellate court should have discretion in these cases where there is clear violation by prosecution without any valid reason.