Justice Brennan, joined by Justices Marshall and Blackmun, agreed that discovery rules are important to fair and accurate criminal adjudication. But he maintained that excluding material defense evidence is ordinarily an arbitrary and disproportionate sanction because it deliberately deprives the jury of evidence that may establish innocence.
In his view, the Compulsory Process Clause and due process require searching scrutiny of restrictions on defense evidence. Under Rock v. Arkansas and Chambers v. Mississippi, a restriction must accommodate legitimate trial interests and cannot be arbitrary or disproportionate to its purpose. Witness preclusion fails that standard when other measures can cure surprise and deter misconduct without distorting the factfinding record.
A continuance would have allowed the prosecution to investigate Wormley, and cross-examination or prosecutorial comment could have exposed the suspicious timing and credibility problems in his account. Brennan argued that credibility ordinarily belongs to the jury, not the judge, and that a late-disclosed witness is not a category of person whom courts may presumptively silence as untrustworthy.
Brennan also argued that direct sanctions against the responsible lawyer, including contempt or professional discipline, are fairer and more effective than punishing the accused through exclusion of favorable evidence. The Illinois rule itself authorized sanctions against counsel, and the record showed counsel’s apparent misconduct but did not show that Taylor personally participated in it.
He would have held that, absent evidence of the defendant’s personal responsibility for the discovery violation, the Compulsory Process Clause per se prohibits precluding criminal defense evidence. The majority’s case-by-case approach, he warned, creates a conflict of interest because defense counsel must argue that the court should punish counsel personally rather than exclude evidence that could acquit the client.