In Barrera v. State, 982 S.W.2d 415 (Tex.Crim.App. 1998), the defendant appealed his conviction by arguing that the trial court erred in failing to apply the law of self-defense to the facts of the case and failing to instruct the jury that a reasonable doubt on the issue of self-defense required acquittal. See Barrera, 982 S.W.2d. at 416. At trial, the defendant did not request a self-defense instruction and did not object to the charge as given. See id. The court of appeals agreed with defendant, opined that the error implicates rights derived from the U.S. Constitution, and analyzed the error under the federal harmless error rule. See id. However, the Texas Court of Criminal Appeals held that the trial court's error did not implicate defendant's federal constitutional rights. See id. at 417. Instead, the Court concluded the failure to apply the law of a case to its facts constituted merely a technical violation of a rule under state law. See Barrera, 982 S.W.2d at 417. The Court opined that this follows from federal decisions concluding that generally, "'instructions to the jury in state trials are matters of state law and procedure not involving federal constitutional issues.'" Id. A constitutional violation occurs only if a reasonable likelihood exists that the jury understood the instructions to allow conviction on proof that fails to meet the Winship standard. Id. Winship held that to convict a defendant, a court's charge must require the jury to find the State proved each element of the charged offense beyond a reasonable doubt. See In re Winship, 397 U.S. 358 (1970). A charge that fails to do so is erroneous. See id. In Barrera v. State, the appellant did not request a self-defense instruction at his trial for attempted murder and aggravated assault, or object to the one given by the court. The trial court gave a self-defense instruction sua sponte. Id. At 416. On appeal from his conviction of attempted murder, Barrera complained the trial court had erred by failing to properly apply the law of self-defense to the facts of the case and by failing to instruct the jury that a reasonable doubt on the issue of self-defense required acquittal. Id. Barrera claimed that because these errors were a violation of his constitutional rights, they should be analyzed under the federal "harmless error" rule and not under the "egregious harm" test required by Almanza for unobjected-to jury charge errors. Id. After holding that the charge was erroneous, the court of criminal appeals stated: the failure to apply the law of a case to its facts does not amount to a federal constitutional error, but is merely a "technical violation of a state-law rule." Brown v. Collins, 937 F.2d 175, 182 (5th Cir.), rehearing en banc denied, 945 F.2d 403 (1991). This conclusion naturally follows from federal decisions which have concluded that "normally . . . instructions to the jury in state trials are matters of state law and procedure not involving federal constitutional issues." United States ex. rel. Waters v. Bensinger, 507 F.2d 103, 105 (7th Cir. 1974) (quoting Grundler v. North Carolina, 283 F.2d 798, 802 (4th Cir. 1960). Federal courts considering habeas petitions have announced narrow guidelines for jury charge error that offends the federal constitution: When reviewing a jury charge for constitutional infirmity, we must consider the challenged portion of the charge not "in artificial isolation," but rather "in the context of the overall charge." Cupp v. Naughten, 414 U.S. 141, 146-47, 94 S. Ct. 396, 400, 38 L. Ed. 2d 368 (1973). A constitutional violation occurs only if "there is a reasonable likelihood that the jury understood the instructions to allow conviction on proof insufficient to meet the Winship standard." - In re Winship, 397 U.S. 358, 25 L. Ed. 2d 368, 90 S. Ct. 1068 (1970) (due process clause requires proof beyond a reasonable doubt to establish guilt of a criminal charge; the prosecution must convince the trier of fact of all essential elements of guilt). Victor v. Nebraska, 511 U.S. 1, 6, 114 S. Ct. 1239, 1243, 127 L. Ed. 2d 583 (1994). Justice v. Hoke, 45 F.3d 33, 34 (2nd Cir. 1995). A trial court's failure to apply an otherwise correct defensive jury instruction does not give rise to such a likelihood. (Barrera, 982 S.W.2d at 417.)