People v. Stewart

delivered the Opinion of the Court.

We are reviewing the court of appeals' decision in People v. Stewart, 26 P.3d 17 (Colo.Ct.App.2000), reversing the defendant's assault conviction arising out of an incident in which the vehicle he was driving struck and seriously injured a pedestrian. The court of appeals held that Wayne Robert Stewart's conviction of reckless second degree assault with a deadly weapon, section 18-3-203(1)(d), 6 C.R.S. (2001), violates equal protection of the laws, U.S. Const. Amend. XIV; Colo. Const. Art II, See. 25, because it imposes a more severe penalty for the same behavior proscribed by the vehicular assault statute, section 18-8-205(1)(a), 6 CRS. (2001). In addition to review of this constitutional issue, we granted certiorari to consider whether (1) the court of appeals erred in finding that the trial court committed plain error by failing to give an intervening cause instruction as to second degree assault when the instruction was not requested by the defense; (2) whether the court of appeals erred when it held that an investigating officer, who was not qualified as an expert, should not have been allowed to express his opinion about how the accident occurred; and (8) whether a limited remand is required in order for the trial court to properly consider a defendant's motion for appeal bond.

We reinstate the conviction. Because we conclude that there are reasonable distinctions between the statutes governing reckless second degree assault and vehicular assault, we find no equal protection violation. Therefore, we reverse the court of appeals' decision on this issue. Additionally, we hold that the trial court did not commit plain error in failing to instruct the jury that intervening cause constituted an affirmative defense as to second degree assault. Consequently, we reverse the court of appeals' judgment on this issue. We agree with the court of appeals that the trial court abused its discretion in permitting an investigating officer to testify about his reconstruction of the crime seene without qualifying him as an expert. Because we conclude that the error was harmless, however, no reversal of Stewart's conviction is warranted. Finally, we conclude that a limited remand is not required on the bond issue. Accordingly, we affirm the court of appeals' judgment with respect to this issue.

I. FACTS AND PROCEEDINGS BELOW

The crimes occurred on a Sunday evening in March 1997 when Wayne Stewart left the bar of a restaurant located in a suburban shopping center. As Stewart began to drive his sports utility vehicle out of the shopping center parking lot, he encountered three pedestrians-Richard Ehrmann, Christine Castro, and Jeffrey Pippenger, in that order-walking abreast in the middle of the driving lane. The pedestrians had just left a video rental store and, as they walked to their vehicle, they were looking up at the Hale Bopp comet streaking across the sky. The testimony of disinterested bystanders established that Stewart veered toward the pedestrians at an angle; Ehrmann, who was closest to the traffic lane, was brushed by Stewart's vehicle. A verbal altercation ensued, after which Stewart began driving back and forth at an angle and in an aggressive manner.

The parties dispute how Ehrmann came to land on the hood of Stewart's vehicle. Stewart maintained that as he drove forward and passed Ehrmann, the victim, who was facing him, Ehrmann suddenly vaulted onto the front quarter panel, landing on the vehicle's hood. Just as suddenly, according to Stewart, Ehrmann rolled or jumped off. Stewart argued that a dent was caused by Ehrmann's buttocks as he vaulted onto the hood, landing in a seated position. The People, by contrast, contended that Ehrmann had his back *113to the vehicle when he was hit by it and propelled into the air, landing on the SUV's front quarter panel. They asserted that the dent was caused by Ehrmann's elbow when he was thrown onto the vehicle.

Eyewitnesses testified that Stewart abruptly stopped his vehicle, and Ehrmann rolled off the hood, landing "hard" on the ground next to the driver's side of the SUV. Ehrmann's head landed under the SUV between the front and back wheels. There is conflicting evidence as to whether the defendant stopped his vehicle after Ehrmann rolled off, As Stewart proceeded ahead at a slow rate of speed, the rear driver's side tire ran over Ehrmann's head. Stewart testified that he neither saw Ehrmann lying on the ground after Ehrmann fell off the vehicle nor was aware that he had run over Ehrmann's head. Stewart left the scene without stopping.

As a result of the incident, Ehrmann suffered massive brain injury and lay comatose for approximately two and one-half years. Ultimately, the victim died.

The state charged Stewart with one count of first degree assault against Ehrmann, a class 3 felony in violation of section 18-3-202(1)(a); one count of reckless second degree assault against Ehrmann, a class 4 felony, in violation of section 18-8-208(1)(d), 6 C.R.S. (2001); four counts of violent crime, pursuant to section 16-11-3809, 6 C.R.S. (2001) 1; one count of vehicular assault against Ehrmann, a class 5 felony, in violation of section 18-8-205(1)(a), 6 CRS. (2001); and four counts of reckless endangerment against the other two pedestrians and two bystanders, a class 3 misdemeanor, in violation of section 18-3-208, 6 C.R.S. (2001). Stewart pleaded not guilty to the charges.

At trial, the People contended that Stewart intentionally hit Ehrmann or, in the alternative, that Stewart used his vehicle to scare and intimidate Ehrmann. Stewart took the position described above that Ehrmann jumped onto Stewart's vehicle and that he was unaware that he ran over Ehrmann. The court instructed the jury on several theories of defense. Stewart asserted "intervening cause" as a defense to vehicular assault but not as to any of the other offenses charged.

A jury convicted Stewart of reckless see-ond degree assault of Ehrmann and two counts of reckless endangerment against the other two pedestrians. At the sentencing hearing, the trial court found that Stewart "did drive his car at Mr. Ehrmann in an act of anger," and sentenced Stewart to five years in the Department of Corrections (DOC) for the second degree assault conviction and six months on each of the reckless endangerment counts. Stewart appealed his conviction and sentence as to second degree assault only.

The court of appeals reversed Stewart's conviction and remanded his case with directions. People v. Stewart, 26 P.3d 17 (Colo.Ct.App.2000). Four of its holdings are relevant here.

First, it determined that second degree reckless assault with a deadly weapon is identical to reckless vehicular assault when the deadly weapon is a car. Applying Colorado's equal protection doctrine, the court concluded that the two statutes proscribe the same conduct but impose disparate penalties and that, consequently, Stewart could not be convicted of the more serious offense of see-ond degree assault. In light of Stewart's acquittal of vehicular assault at trial, and because it deemed retrial necessary on other grounds, the court concluded that Stewart could be retried on second degree assault; if convicted, however, he could be punished only as if convicted for vehicular assault.

Second, the court of appeals concluded that the trial court committed reversible error by failing to instruct the jury that "intervening cause" was a defense to second degree assault. This failure amounted to plain error, in the court's view, because the trial court did provide the instruction as a defense to vehicular assault, a charge of which he was acquitted.

*114Third, the court of appeals concluded that the trial court should not have permitted a police officer to offer opinions about the incident without being qualified as an expert.2

Finally, the court of appeals concluded that no remand was necessary for the trial court to retain jurisdiction to consider a defendant's application for an appeal bond filed after the direct appeal commences.

We granted certiorari.

II, ANALYSIS

1. Equal Protection

Stewart argues that his conviction for reckless second degree assault with a deadly weapon violates his right to equal protection because the statutes governing vehicular assault and reckless second degree assault with a deadly weapon proscribe the same conduct but mete out disparate punishments. He asserts that there is no rational distinction between second degree reckless assault, a class 4 felony requiring mandatory sentencing for a term of five to sixteen years,3 and vehicular assault, a class 5 felony that is punishable by one to three years of imprisonment in the presumptive range and two to six years in the aggravated range, and which neither requires a mandatory sentence nor precludes probation. The lack of any rational basis for distinguishing the two offenses, he maintains, coupled with the significant difference in penalty, renders his conviction of second degree assault violative of equal protection by penalizing him more severely for the identical eriminal conduct proscribed by the lesser offense of vehicular assault. We disagree.

The Fourteenth Amendment to the United States Constitution provides in part that no state "shall deny to any person within its jurisdiction the equal protection of the laws." A similar guarantee is implicit in the due process clause of the Colorado Constitution. Colo. Const., art. II, sec. 25. Colorado, however, has taken a stricter view of the protections afforded by our equal protection guarantee than has the United States Supreme Court in interpreting the federal Constitution. The Supreme Court has held that equal protection is not offended when statutes proscribe identical conduct but authorize different penalties. United States v. Batchelder, 442 U.S. 114, 99 S.Ct. 2198, 60 L.Ed.2d 755 (1979).4

By contrast, we have consistently held that if a criminal statute proseribes different penalties for identical conduct, a person convicted under the harsher penalty is denied equal protection unless there are reasonable differences or distinctions between the proseribed behavior. See, eg., People v. Richardson, 983 P.2d 5, 6-7 (Colo.1999); People v. District Court, 964 P.2d 498, 500-01 (Colo.1998); People v. Marcy, 628 P.2d 69, 74 (Colo.1981); People v. Estrada, 198 Colo. 188, 191, 601 P.2d 619, 621 (1979); People v. Calvaresi, 188 Colo. 277, 281-82, 534 P.2d 316, 318 (1975). The statutory classification of crimes must be based on differences that are both real in fact and also reasonably related to the general purposes of the criminal legislation. Richardson, 983 P.2d at 7; District Court, 964 P.2d at 501; Marcy, 628 P.2d at 74-75.

Equally well established is the principle that a single act may violate more than one criminal statute. People v. Owens, 670 P.2d 1233, 1237-38 (Colo.1983); People v. Westrum, 624 P.2d 1302 (Colo.1981). We have emphasized that equal protection is offended only when two statutes forbid identical conduct. Westrum, 624 P.2d at 1303. The general assembly may establish more *115severe penalties for acts that it believes have graver consequences, even if the differences are only a matter of degree. People v. Mozee, 723 P.2d 117, 126 (Colo.1986); People v. Haymaker, 716 P.2d 110, 118 (Colo.1986). Similarly, we have held that the enactment of a specific criminal statute does not preclude prosecution under a general criminal statute unless the statutory language clearly indicates that the legislature intended to limit prosecution to the specific statute. People v. Smith, 938 P.2d 111, 115-16 (1997); Westrum, 624 P.2d at 1303.

To determine whether two statutes proscribe identical conduct, we analyze the elements of each. Richardson, 983 P.2d at 7; Mozee, 723 P.2d 117. We emphasize that this task requires a facial examination of the elements comprising each crime. Because the court of appeals failed to apply the correct analysis in this case, we reject its approach and its conclusion.

Our primary task in construing statutes is to give effect to the legislative purpose underlying the enactment. Medina v. State, 35 P.3d 443, 453 (Colo.2001). To determine legislative intent, we first look to the statutory language itself, giving words and phrases their commonly understood meaning. Padilla v. Sch. Dist. No. 1, 25 P.3d 1176, 1180 (Colo.2001). A statute should be interpreted so as to give consistent, harmonious, and sensible effect to all of its parts. People v. Rickstrew, 775 P.2d 570, 574 n. 8 (1989). In going about this task, we are mindful of the presumption that statutes are constitutional. People v. Fuller, 791 P.2d 702, 705 (Colo.1990). A party asserting the unconstitutionality of a statute has the burden of proving such claim beyond a reasonable doubt. People v. Rostad, 669 P.2d 126, 127 (1983). With these principles in mind, we now turn to the statutes.

The crime of reckless second degree assault with a deadly weapon is defined in section 18-8-208(1)(d), 6 C.R.S. (2001), as follows: "(1) A person commits the crime of assault in the second degree if: ... (d) He recklessly causes serious bodily injury to another person by means of a deadly weapon[.]" As noted above, second degree assault is a class 4 felony carrying a mandatory sentence of five to sixteen years.

Vehicular assault is defined in section 18-3-205, 6 C.R.S. (2001), as follows: "(1)(a) If a person operates or drives a motor vehicle in a reckless manner, and this conduct is the proximate cause of serious bodily injury to another, such person commits vehicular assault." Again, as stated above, vehicular assault is a class 5 felony permitting probation and not mandating incarceration; for those convicted of the charge and sentenced to a term of years, the presumptive sentencing range is one to three years and the aggravated sentencing range is two to six years.

The language of the statutes differs in three primary ways. First, second degree assault applies to a range of unspecified conduct; the defendant can "recklessly 'cause" injury in a multitude of ways. The conduct specified in the vehicular assault statute, on the other hand, is strictly limited to "driving or operating" a motor vehicle.

We have held that "drive" means to exercise "actual physical control" over a motor vehicle. People v. Swain, 959 P.2d 426, 429, 431 (1998)(so holding in context of a DUI case where defendant's keys were in the ignition and the truck's radio was playing, but defendant was asleep or passed out in the front seat); Brewer v. Motor Vehicle Div., Dep't of Revenue, 720 P.2d 564, 566-67 (Colo.1986)(holding under the express consent statute that driving means being "in actual physical control" of a motor vehicle and is not limited to "placing and controlling a vehicle in motion"). The term "operate" is somewhat broader, connoting the action of causing something "to occur ... [or] to cause to function usually by direct personal effort." People v. Gregor, 26 P.3d 530, 532 (Colo.Ct.App.2000)(quoting Webster's Third New International Dictionary 1580-81 (1986)).

An elemental comparison thus illustrates that the two statutes, by their terms, target different conduct. To achieve a conviction under the vehicular assault statute, the prosecution must demonstrate that the defendant drove or operated a motor vehicle. See Britto v. People, 178 Colo. 216, *116218-19, 497 P.2d 325 (1972) (holding that where defendant was in the back seat and a third party was driving, the defendant could not be convicted of vehicular assault for causing the victim to be dragged by the car but noting that such conduct could sustain a conviction for other offenses if the defendant had been properly charged). Accordingly, one who causes serious bodily injury by dint of a motor vehicle that is used as a weapon, but that is not driven or operated, could be convicted of reckless second degree assault with a deadly weapon but not vehicular assault. For example, if an adult locks a child in a car on a sweltering summer day to punish or intimidate the child, the adult obviously is not driving or operating the car. Assuming that the other elements of the crime are met, however, the adult could be charged with reckless second degree assault but not vehicular assault.

The second difference between the statutes relates to eausation. The second degree assault statute applies to one who recklessly "causes" serious bodily injury. Vehicular assault, by contrast, applies where reckless driving is the "proximate cause" of serious bodily injury. Colorado's jury instructions provide that " 'cause' means that act or failure to act which in natural and probable sequence produced the claimed injury." CJI Criminal 9:10, 9(4) (1983). Proximate cause, by contrast, "means a cause which in natural and probable sequence produced the claimed injury. It is a cause without which the claimed injury would not have been sustained." CJI Criminal, 9:10, 9(8) (1983). The plain language of the statutes thus illuminates a significant difference between the laws: second degree reckless assault can apply to acts of omission; vehicular assault cannot.

A variation on the facts of People v. Clary, 950 P.2d 654 (Colo.Ct.App.1997), illustrates how one could be convicted of second degree reckless assault for an act of omission. In Clary, the defendant was an automobile mechanic who worked on the brakes of his own vehicle at the shop where he was employed shortly before he was involved in an accident. Id. at 656. At that time, the defendant's truck was leaking fluids and the brake pedal, when tested, had no pressure. Id. Rather than install new brake pads, the defendant rigged a bungee cord to the brake pedal. Despite being warned by a coworker that such a makeshift system was unsafe, the defendant proceeded to drive the vehicle home; shortly thereafter, he was involved in a two-automobile accident that caused serious bodily injury and death to the occupants of the other vehicle. Id. at 655-56.

In the real case, Clary, the auto mechanic and owner of the defective vehicle he deliberately failed to repair, was also the driver in the accident. If the facts were the same but Clary were not the driver, he could be liable for reckless assault but not vehicular assault. Suppose that Clary lent the truck to a friend without fixing the brakes or warning the friend that the brakes were faulty. A subsequent injury accident while the friend drove the truck would expose Clary to eriminal liability for second degree reckless assault, among other crimes, because of his omissions.

The decision by the General Assembly to punish both affirmative acts and acts of omission under the second degree assault statute, while penalizing only affirmative acts under the vehicular assault statute, is a rational choice among many public policy alternatives. Cf. Rostad, 669 P.2d at 128 (making this point in concluding that the legislature's decision to require proof of proximate cause in criminal proceedings related to the operation of motor vehicles is a reasonable public policy choice).

The third primary difference between see-ond degree assault and vehicular assault lies in the means by which the defendant allegedly caused serious bodily injury. The vehicular assault statute provides that, to be convicted, the defendant's reckless driving or operation of a "motor vehicle" must have proximately caused serious bodily injury. The second degree assault statute requires that the defendant use a "deadly weapon." In order for us to conclude that the two statutes proscribe identical conduct, then, we would have to conclude that a motor vehicle is always a deadly weapon. As we explain below, we decline to adopt a construction of "deadly weapon" that contravenes our case *117law and that defies common sense and common experience.

Section 18-1-901(8)(e), 6 CRS. (2001), provides the statutory definition of deadly weapon:

"Deadly weapon" means any of the following which in the manner it is used or intended to be used is capable of producing death or serious bodily injury:

(D) A firearm, whether loaded or unloaded;

(II) A knife;

(III) A bludgeon; or

(IV) Any other weapon, device, instrument, material, or substance, whether animate or inanimate.

Relevant here is subsection (IV), which applies to items or objects that are not ordinarily thought to be deadly weapons but may become deadly weapons, depending on how they are used. People v. Saleh, 45 P.3d 1272 (Colo.2002) (construing subsection (IV) and holding that when a foot is used as a weapon that causes serious bodily injury, it satisfies the statutory definition of "deadly weapon").

We have consistently held that whether an object is a deadly weapon for the purposes of section 18-1-908(e)(IV) depends on the manner in which the object is used. Saleh, 45 P.3d at 1275-75; People v. Ross, 831 P.2d 1310, 1312 (Colo.1992)(holding that a fist can be a deadly weapon); Bowers v. People, 617 P.2d 560, 562-63 (Colo.1980)(holding that a whiskey bottle may be a deadly weapon depending on how it is used); People v. Bramlett, 194 Colo. 205, 209, 573 P.2d 94, 96 (1977) (stating that any object used in a manner capable of producing death or serious bodily injury is a deadly weapon).

In People v. Saleh, we recently reaffirmed that "[alny object can be a deadly weapon if it is used in a manner capable of producing death or serious bodily injury." 45 P.3d at 1275. There, we rejected the court of appeals' reasoning that section 18-1-901(8)(e)(IV) refers to instruments that "can be used in a manner consistent with their design to inflict serious bodily injury." Id. Instead, we concluded that 18-1-901(8)(e)(IV) "limits the scope of 'deadly weapon' by including only those objects which 'in the manner [they are] used or intended to be used [are] capable of producing death or serious bodily injury'." Id. Thus, we held "that when an object is used in a manner capable of causing death or serious bodily injury, the object used is a deadly weapon within the statutory definition of seetion 18-1-901(8)(e)." Id. at 1276.

Saleh underscores the point that implicit in our deadly weapon analysis of sub-part (IV) is the requirement that the object be used or intended to be used as a weapon. Our holding there, and in the prior caselaw, thus contemplates a two-step inquiry in determining whether an instrument is a deadly weapon. First, the object must be used or intended to be used as a weapon. Grass v. People, 172 Colo. 223, 228, 471 P.2d 602, 604 (1970) (adopting the view that the instruments that are not per se deadly weapons "must ... mean some article or object, which could be and was used as a weapon"). Second, the object must be capable of causing serious bodily injury. Thus, in Saleh, the defendant's foot would not have been deemed a deadly weapon had the defendant not used it as a weapon. Obviously, in the normal course of events, people are not walking on deadly weapons. That the defendant's foot was capable of producing serious bodily injury would be irrelevant for purposes of section 18-1-901(8)(e) had the foot not been deployed as a weapon. The defendant need not intend to cause serious bodily injury; he must merely use as a weapon an object or instrument that is capable of causing such injury. |

The same is true of a motor vehicle. It is not always a deadly weapon under the statutory definition. A motor vehicle may be a deadly weapon, however, depending on how it is used in a particular situation.

The difference between the "deadly weapon" requirement of the second degree assault statute and the "motor vehicle" element of vehicular assault justifies the disparate penalties established by the General Assembly. The legislature could rationally decide that "road rage" or the use of a car as a deadly weapon justifies an increased penalty. At the same time, it could rationally determine *118that it is less reprehensible for one to cause serious bodily injury by mere reckless driving of a vehicle as a vehicle. This court cannot hold that the General Assembly has constitutionally erred in providing a more severe penalty for an act which it believes to be of greater social consequence. People v. Czajkowski, 193 Colo. 352, 356, 568 P.2d 23, 25-26 (1977). Accordingly, we conclude that the difference between "motor vehicle" and "deadly weapon" is both real in fact and also reasonably related to the legislature's purpose of punishing those who use weapons to cause injury. Stewart's right to equal protection under the law was not violated.

2. Offenses Charged

Stewart argues that even if the statutes are not identical, he can be convicted only of the more specific crime, motor vehicle assault, and not of the more general crime, second degree assault. Generally, the prosecution has discretion to determine what charges to file when a defendant's conduct violates more than one statute. See § 18-1-408(7), 6 C.R.S. (2001). There are certain cireumstances in which this general rule does not apply. See, eg., People v. Smith, 938 P.2d 111, 115-16 (Colo.1997); People v. Bagby, 734 P.2d 1059, 1061-62 (Colo.1987).

Stewart has failed to show that his crimes fall into this category. He simply asserts that the General Assembly intended to punish motor vehicle offenses pursuant to the motor vehicle statutes. He cites no authority such as statutory language or legislative history to support his theory and we reject it. The prosecution had discretion to charge second degree assault in this case and the jury verdict convicting Stewart on that charge stands.

Therefore, we reverse the judgment of the court of appeals on this issue.5

3. Jury Instruction Error

Stewart next argues that the trial court committed reversible error by failing sua sponte to instruct the jury that "intervening cause" constituted an affirmative defense to first and second degree assault. The court of appeals agreed, concluding that this failure constituted plain error and thus required the reversal of Stewart's conviction. We reverse.

In this case, Stewart's counsel submitted to the court a package of instructions that were given to the jury as requested by Stewart. Defense counsel affirmatively stated that he had no objections to the instructions when the trial court so inquired. Included among these instructions were two theory-of-the-case instructions, the second of which explained that "intervening cause" was an affirmative defense 6 to the erimes of vehicular assault and careless driving resulting in injury. Stewart's counsel did not request a similar instruction on the first or second degree assault charges, and the trial court did not provide one. The first theory of the case instruction, however, stated that Stewart acted in self defense, and that self defense is an affirmative defense to first and second degree assault.

During deliberations, the jury sent out a question, signed by the foreperson, which inquired in relation to the vehicular assault charge:

If both parties (Ehrmann & Stewart) are culpable to some degree is a conviction warranted?

The trial court replied:

Richard Ehrmann's culpability must be an act of gross negligence which was not reasonably foreseeable by the Defendant. Consider this answer in relationship to [the instruction on the defendant's theory of the case as to vehicular assault or careless driving resulting in injury].

As noted above, the jury acquitted Stewart of vehicular assault and careless driving re*119sulting in injury, and it convicted him of second degree assault and two counts of reckless endangerment. The verdict as to second degree assault, Stewart contends, was erroneous, and the error is attributable to the court's failure to instruct on intervening cause for the first and second degree assault charges. In Stewart's view, the error engendered jury confusion over, and misunderstanding of, causation. Had it correctly understood and applied the relevant law, he maintains, the jury would have acquitted Stewart of second degree assault as well as vehicular assault.

The People contend that we need not address the merits of this claim because any failure to instruct on intervening cause was invited error caused by Stewart. We agree with Stewart and the court of appeals that a nontactical instructional omission generally should be reviewed for plain error.

We acknowledge, however, that on occasion we have declined to review errors, including jury instruction errors, alleged by a party who is responsible for the claimed error under the invited error doctrine. Horton v. Suthers, 43 P.3d 611, 618-19 (Colo.2002); People v. Zapata, T9 P2d 1307, 1309 (Colo.1989)(deciding not to address merits of plain error argument raised by criminal defendant where defendant's counsel prepared and tendered theory of the case instruction about which defendant later complained). However, in Zapata we recognized that some courts have found an exception to the invited error doctrine where the error was not a part of the defendant's trial strategy. 779 P.2d at 1310 n. 4. Because that was not the case in Zapata, however, we declined to consider whether such an exception exists in Colorado law.

The instant case, by contrast, likely presents a case of oversight, not strategy. Although defense counsel tendered an affirmative defense instruction of self defense as to first and second degree assault and the intervening cause instruction as to vehicular assault, thereby providing affirmative defense instructions for each of the major charges, we view the omission of the intervening cause instruction as to first and see-ond degree assault as an oversight in light of the heavy reliance Stewart placed on this theory during trial. Throughout, he maintained that Ehrmann abruptly leapt upon the vehicle, although he also argued that he acted in self defense and that the incident was an accident. While it is possible that Stewart elected to emphasize the theory of self defense for strategic reasons, and concomitantly wished to deemphasize intervening cause as an affirmative defense to first and second degree assault, we assume without deciding that the omission was an oversight.

In light of the likely nontactical basis of the omission, we find Chief Justice Quinn's special concurrence in Zapata particularly persuasive. There, he stated that if "claimed error is truly 'plain, in that it so undermines the fundamental fairness of the trial as to cast serious doubt on the reliability of the result, it would seem ... that an appellate court, rather than refusing to address the issue by a wooden application of the invited error rule, should come to grips with the defendant's claim in order to prevent a possible miscarriage of justice." 779 P.2d at 1811 (Quinn, C.J., specially concurring). He ree-ognized that the although invited error in most cases will result from defense counsel's inadvertence or negligence, it is the defendant who must bear the stigma of a conviction and the burden of prison time; accordingly, application of the plain error doctrine, rather than the invited error doctrine, "does no more than provide an appellate court with the necessary means to reverse a criminal conviction obtained in derogation of fundamental fairness." Id. Additionally, although such errors likely will be considered in post-conviction proceedings under Crim. P. 35(c), an appellate court's willingness to consider them on direct appeal would "obviate any additional injustice" resulting from what may later be deemed an invalid conviction. Id. at n. 2.

We agree. Where it appears that an error or omission in jury instructions is due to inadvertence or attorney incompetence, the reviewing court should apply the doctrine of plain error. Where, however, the omission is strategic, the invited error doctrine should be invoked. Thus, " 'wherer a party *120assumes a certain position in a legal proceeding, and succeeds in maintaining that position, he may not thereafter, simply because his interests have changed, assume a contrary position' " People v. Garcia, 826 P.2d 1259, 1263 (Colo.1992) (quoting Davis v. Wakelee, 156 U.S. 680, 689, 15 S.Ct. 555, 39 L.Ed. 578 (1895)).

In this case, as noted above, it appears that the alleged error was the result of inadvertence. Accordingly, we review the instructional omission for plain error. Finding none here, we reverse the court of appeals' decision on this issue.

It is axiomatic that a trial court is obligated to instruct the jury correctly on the law applicable to the case. People v. Cowden, 735 P.2d 199 (Colo.1987); see also Hansen, 957 P.2d at 1384. A defendant also is entitled to a theory of the case instruction if the record contains any evidence, even highly improbable testimony by the defendant, to support the theory. People v. Nunez, 841 P.2d 261, 264-65 (Colo.1992); People v. Fuller, 781 P.2d 647, 651 (Colo.1989).

While the court is duty-bound to instruct the jury, "it is equally the duty of counsel to assist the court by objection to erroneous instructions, and by the tender of instructions covering matters omitted by the court." Fresquez v. People, 178 Colo. 220, 231, 497 P.2d 1246, 1252 (1972) (internal citation omitted); Willis v. People, 114 Colo. 334, 164 P.2d 733 (1945). A defendant must make all objections she has to instructions prior to their submission to the jury. See Crim. P. 30. The purpose of this rule is to enable the trial judge to prevent error from occurring and to correct an error if improper instructions are tendered. People v. Barker, 180 Colo. 28, 32, 501 P.2d 1041, 1043 (1972). Where counsel fails to object or to tender instructions on the omitted issues, appellate courts will not consider any error assigned to the giving, or failure to give, pertinent instructions unless there was plain error. Crim. P. 30; Crim. P. 52; see also People v. Tilley, 184 Colo. 424, 427, 520 P.2d 1046, 1047 (1974)(collecting cases).

Plain error analysis applies here because Stewart failed to comply with our rules of eriminal procedure. Here, as noted above, Stewart's counsel, with the assistance of special co-counsel brought in to help craft the appropriate instructions, drafted a set of instructions, which the trial court delivered as requested. Stewart affirmed that he had no objection to the instructions when asked by the court; he did not object to the omissions as Criminal Procedure Rule 30 requires. Thus, under the legal principles outlined above, we review the alleged error under the plain error rubric.

Plain error is grave error that seriously affects the substantial rights of the accused. Espinoza v. People, 712 P.2d 4746, 478 (Colo.1985). It is an error that is "both obvious and substantial." Barker, 180 Colo. at 32, 501 P.2d at 1043. In the context of jury instructions, we have refused to find plain error unless a review of the entire record demonstrates a "reasonable possibility that the improper instruction contributed to the defendant's conviction." People v. Dillon, 655 P.2d 841, 845 (Colo.1982). It is unlikely that an erroneous instruction will be considered plain error if the evidence of the defendant's guilt is overwhelming. Espinoza, 712 P.2d at 478; cf. Barker, 180 Colo. at 33, 501 P.2d at 1043.

In this case, Stewart maintains that the verdict would have been different had the affirmative defense instruction been given. As evidence of this belief, he points to the jury's question to the trial court referencing the vehicular assault instruction and inquiring what they should do if both parties were culpable to some degree. As noted above, the instruction to which the court referred them-defendant's theory of the case as to vehicular assault-included the affirmative defense of intervening cause as to that charge only. The jury's subsequent acquittal of Stewart on the vehicular assault charge but its conviction of him on the see-ond degree assault charge, he maintains, is attributable to the omission of the affirmative defense of intervening cause as to see-ond degree assault.

We disagree. A defendant is responsible fo