Associate Chief Justice NEHRING, opinion of the Court:
¶ 1 A jury convicted Jesus Jimenez of aggravated robbery. The jury also found that Mr. Jimenez was subject to a one-year enhancement of his sentence because a dangerous weapon, a gun, was used in the course of the robbery. Mr. Jimenez appealed his conviction. The court of appeals affirmed. Mr. Jimenez contends that the court of appeals erred when it rejected his claim that his counsel was ineffective and his claim that the plain error exception to our preservation rules applied in his case. Mr. Jimenez's arguments are based on the contention that the State failed to prove he had knowledge of the principal's possession of a dangerous weapon. We first clarify the mental state required for the dangerous weapon aggravator in Utah Code section 76-6-302(1)(a). We hold that, because the legislature has made no indication that it is a strict liability offense, the statutory aggravator requires the culpable mental state of recklessness. Mr. Jimenez's claims on appeal do not require reversal, however, because he has not demonstrated that the errors caused him prejudice. We therefore affirm the conviction of aggravated robbery with a one-year penalty enhancement.
¶ 2 On August 15, 2007, Mr. Jimenez repeatedly drove past a salon owned by Faviola Hernandez.
¶ 3 Mr. Jimenez and Mr. Mateos spoke to each other in Spanish while Mr. Jimenez drove back and forth in front of the salon. Ms. Matern could not relate details of the conversation because she understands very little Spanish. Despite the language barrier, Ms. Matern became suspicious of the subject of the conversation and driving activity after Mr. Jimenez drove past the salon for the third time. Mr. Jimenez finally stopped the car just south of the salon. Mr. Mateos exited the car. Mr. Jimenez then turned the car around and told Ms. Matern to get down in the back seat. When she refused, he repeated that she "had better get down."
¶ 4 Mr. Mateos entered the salon. There, he found Faviola with a customer, Leonel Hernandez. Also inside were Laura and Junior, who had returned from the school playground. Mr. Mateos pointed a gun at Leonel, told him to get on the ground, and demanded money. Mr. Mateos also pointed the gun at Laura and Junior and told them to get on the ground. Faviola said, "No. No, not the kids." Mr. Mateos continued to demand money. Faviola went to the back of the salon and returned with a gun she kept for protection. The weapon failed to protect Faviola. Mr. Mateos shot her in the chest and left the salon. Leonel got up, locked the door to the salon, and called 911.
¶ 5 Faviola told Leonel that she had been shot and then collapsed. Leonel attempted to stop the bleeding with a towel, but when the police arrived at the salon, Faviola was dead.
¶ 6 Hearing the gunshot in the salon, Ms. Matern told Mr. Jimenez to leave, but Mr. Jimenez refused. Mr. Mateos returned to the car and got into the back seat. Mr. Jimenez drove to a nearby Wal-Mart where Mr. Mateos exited the back seat, still holding the gun. Mr. Mateos changed his shirt. Mr. Jimenez and Mr. Mateos then removed the car's stereo and hid the gun in the stereo space.
¶ 7 Mr. Jimenez was convicted as an accomplice to criminal homicide and to aggravated robbery with a one-year penalty enhancement. The court of appeals affirmed. We granted certiorari to determine whether the court of appeals erred in rejecting Mr. Jimenez's appellate arguments of ineffective assistance of counsel and plain error in relation to his conviction for aggravated robbery and the imposition of a penalty enhancement. We have jurisdiction under Utah Code section 78A-3-102(3)(a).
¶ 8 On certiorari, we review a decision of the court of appeals for correctness.
¶ 9 The court of appeals held that the aggravated robbery statute "do[es] not state that accomplice liability for aggravated robbery requires that the accomplice knew a weapon was present" when the crime was committed.
This court has stated that "[u]nder the Utah Criminal Code, a crime may be a strict liability crime only if the statute specifically states it to be such."
¶ 10 Generally, to be found guilty of an offense under an accomplice liability theory, the accomplice must "act[] with the mental state required for the commission of [that] offense."
¶ 11 The aggravated robbery statute contains no indication that the general rules of mental culpability do not apply. In contrast to the current version of Utah's unlawful sexual intercourse statute, the robbery statute contains no language indicating that the aggravator imposes strict liability.
¶ 12 Having determined that the State was required to prove that Mr. Jimenez was at least reckless regarding the use of a gun in the robbery, we turn now to his ineffective assistance of counsel claim. The Supreme Court established a two-part test for evaluating a defendant's claim of ineffective assistance of counsel: "First, the defendant must show that counsel's performance was deficient.... Second, the defendant must show that the deficient performance prejudiced the defense."
¶ 13 The trial court asked Mr. Jimenez's counsel, "Do you believe that [the State] ha[s] to show prior knowledge that [the principal] had a gun on him?" Mr. Jimenez's counsel replied, "No, just that he was going in ... [to][c]ommit the robbery." Consequently, Mr. Jimenez did not have the opportunity to argue that even if he could be found guilty of robbery, he did not have the requisite mental state for the dangerous weapon aggravator. The State counters that counsel made a reasonable strategic choice to argue that there was insufficient evidence to prove Mr. Jimenez knew Mr. Mateos was going to commit a robbery at all. The State asserts that it would have weakened the credibility of the defense to argue that Mr. Jimenez had no knowledge of the robbery, but if he did know about the robbery, he did not know about the gun. It may have been reasonable for counsel to focus on the robbery itself instead of the dangerous weapon aggravator, but it was not reasonable to relieve the State of its burden to prove that Mr. Jimenez had the mental state required for aggravated robbery. Failing to instruct the jury on the mental component of aggravated robbery served no tactical purpose. Counsel's performance therefore fell below an objective standard of reasonableness.
¶ 14 Mr. Jimenez has not established, however, that his defense was prejudiced by counsel's errors. The evidence indicating that Mr. Jimenez was aware of the gun is strong. The court of appeals listed the evidence as follows:
Furthermore, Mr. Jimenez has not argued on appeal that he was not reckless with regard to the possibility that a gun would be used. Our law provides that one acts recklessly when one is
Mr. Jimenez's theory on appeal is centered on the lack of evidence that he knew Mr. Mateos had a gun when he left the car to commit the robbery. Mr. Jimenez argues that "there is evidence from the testimony of Cassandra Matern that both she and Jimenez were aware of the gun after Mateos returned from [the salon]" and that Ms. Matern "was surprised when she heard a shot coming from [the salon]." This argument acknowledges that before the "immediate flight"
¶ 15 The lack of prejudice is also dispositive in Mr. Jimenez's plain error claim, which requires the defendant to show that the error was harmful.
¶ 16 Utah's dangerous weapon enhancement statute expressly requires the defendant to have knowledge that the weapon was present. The statute provides,
¶ 17 Mr. Jimenez argues that he was deprived of effective assistance of counsel because his defense counsel failed to request the proper jury instruction for the dangerous weapon enhancement. Neither the jury instructions nor the jury verdict form asked about Mr. Jimenez's knowledge that a dangerous weapon was present. Jury instruction 41 read, "You are instructed that under Utah law, if in the commission or furtherance of an Aggravated Robbery a defendant uses a dangerous weapon, he is subject to to [sic]
¶ 18 Defense counsel should have objected to the instructions because they did not include both elements required by the statute: use of a dangerous weapon and knowledge by the defendant that a dangerous weapon was present. Defense counsel's performance in relation to the sentencing enhancement was clearly deficient.
¶ 19 Mr. Jimenez next "must show that the deficient performance prejudiced the defense."
¶ 20 The lack of prejudice is also dispositive of Mr. Jimenez's manifest injustice claim. Manifest injustice is synonymous with the plain error standard,
¶ 21 In Utah's aggravated robbery statute, use of a dangerous weapon requires the culpable mental state of recklessness. Utah's dangerous weapon enhancement statute requires the culpable mental state of knowledge. Because the evidence is strong that Mr. Jimenez knew Mr. Mateos used a gun during the robbery, Mr. Jimenez cannot show that errors made by counsel or the court harmed his defense. We therefore affirm the verdict in this case.