What is the current state of the law on the right to exclude "repetitive" or "only marginally relevant" evidence from a criminal trial?

"The United States Constitution guarantees criminal defendants a meaningful opportunity to present a defense. [Citation.] Evidence that falls short of exonerating a defendant may still be critical to a defense. [Citation.]" (People v. Cash (2002) 28 Cal.4th 703, 727.) Nevertheless, "the Constitution permits judges 'to exclude evidence that is "repetitive . . . , only marginally relevant" or poses an undue risk of "harassment, prejudice, [or] confusion of the issues." ' [Citations.]" (Holmes v. South Carolina (2006) 547 U.S. 319, 326-327.)