In Bruton v. United States, 391 U.S. 123, 126, 88 S. Ct. 1620, 1622, "the United States Supreme Court held that extrajudicial statements of a co-defendant who is not subject to cross-examination may violate the Confrontation Clause." State v. Grimes, 1999 MT 145, ¶ 27, 295 Mont. 22, 982 P.2d 1037. Bruton thus "bars the introduction of a co-defendant's post-arrest statements implicating other defendants when the co-defendant will not testify at trial." Grimes, ¶ 19 (citing Bruton, 391 U.S. at 126, 88 S. Ct. at 1622). The Montana Supreme Court adopted Bruton in State v. Fitzpatrick, 178 Mont. 530, 569 P.2d 383 (1977).
Although the Montana Supreme Court has not specifically cited a standard of review for Bruton violations, we have stated:
We will review a district court's evidentiary decision to determine whether it abused its discretion. There is no discretion, however, in properly interpreting the Sixth Amendment. We review a district court's conclusions of law and interpretations of the Constitution or the rules of evidence, de novo.
State v. Mizenko, 2006 MT 11, ¶ 8, 330 Mont. 299, 127 P.3d 458 (internal citations omitted). See also State v. Spencer, 2007 MT 245, ¶ 14, 339 Mont. 227, 169 P.3d 384 ("We review de novo a district court's interpretation of the Sixth Amendment. We review a district court's evidentiary rulings for abuse of discretion. A court abuses its discretion when it acts arbitrarily, without employing conscientious judgment, or exceeds the bounds of reason, resulting in substantial injustice.") (internal citations omitted).