dissenting.
For the reasons I have twice before stated, Smith v. Jago, 470 U. S. 1060 (1985) (dissenting), Taliaferro v. Maryland, 461 U. S. 948 (1983) (dissenting), I dissent from the Court’s refusal to resolve the important question, which has divided the lower courts, of when, if ever, a State may exclude a defense witness on account of a criminal defendant’s failure to comply with a discovery rule.