In the case of Hill v. Lockhart, William James Hill Jr., a prisoner serving time for first-degree murder and theft charges in Arkansas, appealed his conviction on the grounds that he had received ineffective legal counsel during plea negotiations. He claimed that his attorney misled him about parole eligibility, leading him to accept a guilty plea under false pretenses. The Supreme Court held that in order to successfully challenge a guilty plea based on ineffective assistance of counsel, the defendant must show not only that their lawyer's performance was deficient but also establish "a reasonable probability" they would have insisted on going to trial if properly advised. In this case, since Mr. Hill did not assert innocence or offer any credible claim suggesting he would've opted for trial over pleading guilty if correctly informed about parole eligibility rules by his attorney - thus failing to satisfy both prongs of Strickland test (deficient performance and prejudice), his appeal was denied.

In the dissenting opinion for Hill v. Lockhart, Justice Brennan, joined by Justice Marshall, argued that a defendant's decision to plead guilty is not truly voluntary if it is based on incorrect advice from counsel about parole eligibility. They contended that the majority's application of the "prejudice" requirement was too narrow and failed to consider whether a reasonable probability existed that, but for his attorney’s errors, the defendant would have insisted on going to trial. The dissenters believed this standard should be applied even when defendants are misinformed about collateral consequences like parole eligibility. In their view, such misinformation could significantly impact a defendant's decision-making process and thus undermine the fairness of plea bargaining proceedings.