Does a defendant have an unfettered right to introduce evidence that is incompetent, privileged or otherwise inadmissible under the rules of evidence?

A defendant does not have an unfettered right to introduce evidence that is incompetent, privileged, or otherwise inadmissible under the rules of evidence. (Montana v. Egelhoff (1996) 518 U.S. 37, 42 [116 S.Ct. 2013].) In particular, the exclusion of relevant evidence due to a defendant's failure to comply with procedural requirements does not violate the Constitution. (Ibid.) Here, the trial court did not prevent Perysian from presenting a defense, but simply rebuffed his attempt to present in an untimely fashion and without a showing of due diligence some additional, cumulative evidence. The court's refusal was neither a violation of Perysian's constitutional rights nor of state law.