What is the test for a defendant's right to access expert testimony at trial?

The Fourteenth Amendment of the United States Constitution guarantees a criminal defendant the due process right to present witnesses in support of a defense, but that right is "'subject to reasonable restrictions.'" (People v. Mickel (2016) 2 Cal.5th 181, 218.) The rules of evidence are reasonable restrictions on those rights and thus generally "'do not impermissibly infringe on the accused's right to present a defense.'" (Ibid.) Similarly, "the right to effective assistance of counsel encompasses entitlement to defense experts" when they are necessary for a "fair trial on the issue of guilt." (People v. Stuckey (2009) 175 Cal.App.4th 898, 918.) This right, however, is also subject to the reasonable restrictions in the Evidence Code. (See ibid.)

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