In McMann v. Richardson, 397 U.S. 759, 25 L. Ed. 2d 763, 90 S. Ct. 1441 (1970), state prisoners brought habeas corpus cases in federal court, alleging that their guilty pleas were motivated by involuntary confessions. The Court said: A conviction after trial in which a coerced confession is introduced rests in part on the coerced confession, a constitutionally unacceptable basis for conviction. It is that conviction and the confession on which it rests that the defendant later attacks in collateral proceedings. The defendant who pleads guilty is in a different posture. He is convicted on his counseled admission in open court that he committed the crime charged against him. The prior confession is not the basis for the judgment, has never been offered in evidence at a trial, and may never be offered in evidence. ... What is at stake in this phase of the case is not the integrity of the state convictions obtained on guilty pleas, but whether, years later, defendants must be permitted to withdraw their pleas, which were perfectly valid when made, and be given another choice between admitting their guilt and putting the State to its proof. ... This would be an improvident invasion of the State's interests in maintaining the finality of guilty-plea convictions that were valid under constitutional standards applicable at the time. It is no denigration of the right to trial to hold that when the defendant waives his state court remedies and admits his guilt, he does so under the law then existing; further, he assumes the risk of ordinary error in either his or his attorney's assessment of the law and facts. Although he might have pleaded differently had later decided cases then been the law, he is bound by his plea and his conviction unless he can allege and prove serious derelictions on the part of counsel sufficient to show that his plea was not, after all, a knowing and intelligent act. McMann, 397 U.S. at 773-74.