dissenting.
The majority and I agree that instruction number eight contains an incorrect statement of the law. The majority concludes that because Joseph Hugh Campbell’s attorneys failed to object to the defective instruction, Rule 5A:18 bars our consideration of that issue.2 I believe that the “ends of justice” exception to the Rule *43must be invoked and, further, that the error in giving the instruction was not harmless. Therefore, I dissent.
“[W]hen a principle of law is vital to a defendant in a criminal case, a trial court has an affirmative duty properly to instruct a jury about the matter.” Jimenez v. Commonwealth, 241 Va. 244, 250, 402 S.E.2d 678, 681 (1991). That duty arises even when “trial counsel neglected to object to the instruction.” Id. at 248, 402 S.E.2d at 679. Obviously, the proper description of the elements of the offense was vital to the defendant. Instruction number eight was so defective that it allowed the jury to convict Campbell of forgery even if the jury concluded that Campbell lacked an intent to defraud. Intent to defraud, however, is a necessary element of forgery. Fitzgerald v. Commonwealth, 227 Va. 171, 173, 313 S.E.2d 394, 395 (1984).
[A]n essential of the due process guaranteed by the Fourteenth Amendment [is] that no person shall be made to suffer the onus of a criminal conviction except upon sufficient proof — defined as evidence necessary to convince a trier of fact beyond a reasonable doubt of the existence of every element of the offense.
Jackson v. Virginia, 443 U.S. 307, 316 (1979)(emphasis added). The jury cannot be said to have reached the level of certitude constitutionally required to convict when the jury was instructed that non-criminal conduct was sufficient to satisfy a mens rea element of the offense.
Unless [the appropriate] elements-are defined by instructions available to the members of the jury during their deliberation, they cannot properly determine whether the Commonwealth has carried its burden. . . . “It is always the duty of the court at the proper time to instruct the jury on all principles of law applicable to the pleadings and the evidence (emphasis added)”, and “a correct statement of the law applicable to the case, when the law is stated, ... [is one of the] essentials of a fair trial.”
*44Dowdy v. Commonwealth, 220 Va. 114, 116, 255 S.E.2d 506, 508 (1979(citations omitted); see also Darnell v. Commonwealth, 6 Va. App. 485, 488, 370 S.E.2d 717, 719 (1988).
The misstatement of law relieved the Commonwealth of its burden to prove criminal intent because the trial judge improperly informed the jury that it could convict Campbell even if the jury found that Campbell lacked the requisite mens rea. Thus, the jury could have believed Campbell’s defense — that he had no intent to defraud because his statement to the clerk who changed the record was only intended as a joke — and yet convicted him by finding that his conduct “tended to impair a governmental function.” This occurrence deprived Campbell of the process that he was due.
“There is always in litigation a margin of error, representing error in factfinding, which both parties must take into account. Where one party has at stake an interest of transcending value — as a criminal defendant his liberty — this margin of error is reduced as to him by the process of placing on the other party the burden of . . . persuading the factfinder at the conclusion of the trial of his guilt beyond a reasonable doubt.”
In re Winship, 397 U.S. 358, 364 (1970)(quoting Speiser v. Randall, 357 U.S. 513, 525-26 (1958)). This doctrine, which is the cornerstone of our system of criminal justice, “requires more than simply a trial ritual.” Jackson, 443 U.S. at 316-17.
In Brown v. Commonwealth, 8 Va. App. 126, 380 S.E.2d 8 (1989), this Court emphasized that “[although the ends of justice exception is narrow and is to be used sparingly, [the Court will not place] too restrictive an interpretation upon Mounce [v. Commonwealth, 4 Va. App. 433, 357 S.E.2d 742 (1987)].” Id. at 132, 380 S.E.2d at 11. Specifically, the Court explained:
The language in Mounce that to avail himself of the rule the defendant had to affirmatively show [that] “a miscarriage of justice [has] occurred, not . . . that a miscarriage might have occurred” requires that the error be clear, substantial and material.
*45Id. (emphasis in original). Unquestionably, the error in instructing this jury meets that standard. No amount of sophistry can eliminate the possibility that the jury believed the defense testimony, rationally applied the facts, as believed, to the incorrectly drawn instruction, and convicted Campbell.
The resolution of this dilemma is not found in weighing this hypothesis of innocence against the quantum of proof that the Commonwealth offered in support of guilt. If the jury believed the testimony of Campbell, as it was entitled to do, the quantum of contrary evidence was irrelevant.
Traditional principles dictate, both in the civil and criminal law, that the determination of a witness’ credibility is within the fact finder’s exclusive purview because he has the best opportunity to observe the appearance and demeanor of the witness.
“The credibility of witnesses is a question exclusively for the jury, and where a number of witnesses testify directly opposite to each other, the jury is not bound to regard the weight of the evidence as equally balanced, they have the right to determine from the appearance of the witnesses on the stand, their manner of testifying, and their apparent candor and fairness, their apparent intelligence, or lack of intelligence, and from all the other surrounding circumstances appearing on the trial, which witnesses are more worthy of credit, and to give credit accordingly.”
Goodyear Tire & Rubber Co. v. Pierce, 5 Va. App. 374, 381, 363 S.E.2d 433, 437 (1987)(quoting Zirkle v. Commonwealth, 189 Va. 862, 870, 55 S.E.2d 24, 29 (1949)).
The assertion that there was “an abundance of evidence” or that the “evidence is overwhelmingly” of Campbell’s guilt is not a sufficient basis upon which to deprive Campbell of his right to a jury trial. Campbell is entitled to have a jury trial in which “ ‘the law has been clearly stated [to the jury] and . . . the instructions cover all issues which the evidence fairly raises.’ ” Darnell, 6 Va. App. at 488, 370 S.E.2d at 719. A fundamental hallmark of a fair trial is that “ ‘instructions . . . should inform the jury as to the law of the case applicable to the facts in such a manner that [the *46jury] may not be misled.’ ” Cooper v. Commonwealth, 2 Va. App. 497, 500, 345 S.E.2d 775, 777 (1986).'
The Commonwealth is not entitled to a directed verdict on appeal when the trial judge erroneously instructs the jury as to an essential and necessary element of the charged offense. Our inquiry is not whether it would have been difficult for a rational trier of fact to have reached any other conclusion, but whether “the error did not affect the verdict.” Lavinder v. Commonwealth, 12 Va. App. 1003, 1005, 407 S.E.2d 910, 911 (1991). If we give effect to the presumption that a jury follows the trial judge’s instructions, LeVasseur v. Commonwealth, 225 Va. 564, 589, 304 S.E.2d 644, 657 (1983), cert. denied, 464 U.S. 1063 (1984), it is not appropriate for this Court to affirm a conviction when the jury could have based its decision on otherwise legally innocent behavior. Where the error relates not to the jury’s consideration of improperly admitted evidence, but to a jury’s legally improper application and consideration of wholly proper evidence, it cannot be said that the erroneous instruction “did not affect the verdict,” Lavinder, 12 Va. App. at 1005, 407 S.E.2d at 911, or that Campbell received “a fair trial on the merits and [that] substantial justice has been reached,” Code § 8.01-678. “It is elementary that a jury must be informed as to the essential elements of the offense; a correct statement of the law is one of the ‘essentials of a fair trial.’ ” Darnell, 6 Va. App. at 488, 370 S.E.2d at 719 (quoting Dowdy, 220 Va. at 116, 255 S.E.2d at 508).
The error was patently harmful and was “so contrary to fundamental notions of justice that to permit it to pass uncorrected would seriously undermine the integrity of our judicial system.” Brown, 8 Va. at 133, 380 S.E.2d at 11. “The state’s interest in prevailing at trial and upholding the verdict on appeal must be tempered by its duty to work for a just, fair and accurate adjudication of criminal cases.” Id. at 133 n.3, 380 S.E.2d at 11 n.3 (emphasis added). For these reasons, I would reverse the conviction and remand for a new trial.
“No ruling of the trial court . . . will be considered as a basis for reversal unless the objection was stated together with the grounds therefor at the time of the ruling, except *43for good cause shown or to enable the Court of Appeals to attain the ends of justice.” Rule 5A:18.