delivered the opinion of the court:
Defendant, Ryan M. Watson, was charged by the City of Naperville (City) with driving while under the influence of alcohol in violation of an ordinance (see Naperville Municipal Code § 11 — 1—1) adopting the provisions of the Illinois Vehicle Code (625 ILCS 5/1 — 100 et seq. (West 1994)) by reference. Following a jury trial, defendant was found guilty and was sentenced to one year of court supervision and a $250 fine. The appellate court affirmed defendant’s conviction (No. 2 — 94—0911 (unpublished order under Supreme Court Rule 23)), and this court allowed defendant’s petition for leave to appeal (155 Ill. 2d R. 315). The issues raised on appeal are: (1) whether defendant was shown to be in "actual physical control” of his vehicle; and (2) whether defendant was entitled to raise, and instruct the jury on, the affirmative defense of necessity. We affirm.
BACKGROUND
On June 3, 1993, at about 4:30 a.m., two Naperville police officers discovered defendant asleep in his car. The car was parked with its engine running in the parking lot of an apartment complex in Naperville. Defendant was lying across the front seat with his head on the passenger’s side. The officers had difficulty rousing defendant, and when they did, defendant appeared disoriented. Defendant told the officers that he was sleeping in his car before driving home because he had had too much to drink. The officers testified that defendant’s performance in field sobriety tests indicated to them that he was under the influence of alcohol. At that point defendant was arrested. Later, defendant *401submitted to a breathalyzer test which indicated an alcohol concentration of 0.18.
Defendant testified that at about 5 p.m. on June 2, 1993, he picked up his girlfriend, Danielle, and drove her to a party at his home in Bolingbrook. At the time, Danielle was living with a friend in Naperville. Defendant had been drinking, and when Danielle was ready to leave the party, he explained to her that he could not drive her home because he had had too much to drink. Instead, Danielle drove defendant’s car to her friend’s apartment in Naperville and defendant accompanied her as a passenger. They arrived at about 12:30 a.m. Defendant testified that he planned to stay with Danielle at her friend’s apartment and that there was "no way” that he would drive back to Bolingbrook. Instead of staying in the apartment, however, defendant remained in his car in the apartment complex’s parking lot. Danielle’s testimony corroborated defendant’s account of these events. The trial court barred the defense from introducing evidence regarding the reason defendant did not stay in the apartment. The defense sought to offer testimony that Danielle’s friend’s mother would not allow defendant to stay in the apartment.
Defendant additionally testified that it was very cold in the car and at about 2:30 a.m. he went back to the apartment and asked for a coat or a blanket. Defendant was given a coat, and when he returned to his car he turned on the engine so he could run the heater. Defendant then went to sleep in the car. The parties stipulated that defendant did not actually drive his car during the evening of June 2 or the morning of June 3.
ANALYSIS
Section 11 — 501(a) of the Illinois Vehicle Code provides in pertinent part that a person shall not "drive or be in actual physical control of any vehicle” while the alcohol concentration of his or her blood or breath is *4020.10 or more or the person is under the influence of alcohol. 625 ILCS 5/11 — 501(a) (West 1994). While it is undisputed that defendant did not drive his vehicle during the relevant time frame, the City prosecuted defendant under the theory that he was in actual physical control of the vehicle. Defendant argues that the evidence conclusively shows that he had no intention of driving and only used the vehicle as stationary shelter where he could "sleep off’ the effects of the alcohol he had consumed. Defendant maintains that under these circumstances he was not in "actual physical control” of the vehicle and his conviction must be reversed.
A person need not drive to be in actual physical control of a vehicle, nor is the person’s intent to put the car in motion relevant to the determination of actual physical control. See People v. Davis, 205 Ill. App. 3d 431, 435 (1990). The issue of actual physical control is determined on a case-by-case basis giving consideration to factors such as whether the motorist is positioned in the driver’s seat of the vehicle, has possession of the ignition key and has the physical capability of starting the engine and moving the vehicle. See Davis, 205 Ill. App. 3d at 435; People v. Heimann, 142 Ill. App. 3d 197, 199 (1986). In a number of cases, individuals discovered sleeping in vehicles'have been found to be in actual physical control. See Davis, 205 Ill. App. 3d 431; People v. Scapes, 247 Ill. App. 3d 848 (1993); People v. Cummings, 176 Ill. App. 3d 293 (1988); People v. Brown, 175 Ill. App. 3d 676 (1988); People v. Karjala, 172 Ill. App. 3d 871 (1988).
Some controversy has arisen as to how to treat the individual who recognizes that alcohol consumption has impaired his ability to drive and who chooses to "sleep it off” in a parked vehicle. In People v. Guynn, 33 Ill. App. 3d 736, 739 (1975), the court stated, "[w]e do not see anything which would imply a legislative intent or *403public policy to permit an intoxicated person to 'sleep it off’ behind the wheel of a parked car, although that might be preferable to having him drive a car while intoxicated. A person behind the wheel of a parked car can readily move into a position where he can endanger other persons, property or vehicles.” Other Illinois decisions have likewise refused to recognize the defense of "sleeping it off.” See People v. Brown, 175 Ill. App. 3d 676, 679 (1988); People v. Barlow, 163 Ill. App. 3d 281, 287 (1987); see also People v. Karjala, 172 Ill. App. 3d 871 (1988).
However, dicta in People v. Cummings, 176 Ill. App. 3d 293 (1988), advocated a different rule. In Cummings, the defendant’s car was found in a ditch with the defendant passed out behind the steering wheel. The defendant testified that he began drinking only after his car had become stuck in the ditch. In the course of its analysis, the Cummings court expressed its concern that "through time and expansion by subsequent court rulings, Guynn may have become counterproductive to society’s goal of providing safe highways.” Cummings, 176 Ill. App. 3d at 296. The court explained:
"For the intoxicated person caught between using his vehicle for shelter until he is sober or using it to drive home, Guynn encourages him to attempt to quickly drive home, rather than to sleep it off in the car, where he will be a beacon to police.
We believe it would be preferable, and in line with legislative intent and social policy, to read more flexibility into Guynn. In those rare instances where the facts show that a defendant was furthering the goal of safer highways by voluntarily 'sleeping it off* in his vehicle, and that he had no intent of moving the vehicle, trial courts should be allowed to find that the defendant was not in 'actual physical control’ of the vehicle for purposes of section 11— 501.” Cummings, 176 Ill. App. 3d at 296-97.
See also People v. Barlow, 163 Ill. App. 3d 281, 288 (1987) (Karns, P.J., dissenting) ("contrary to the statement in *404 [Guynn], I see nothing wrong with defendant getting into his truck to 'sleep it off ”).
Nonetheless the Cummings court affirmed the defendant’s conviction, concluding that the case was not one of the "rare instances” it had described, "but instead involve[d] the frequently found circumstance of an intoxicated defendant sleeping in his car after driving it into a ditch.” Cummings, 176 Ill. App. 3d at 297. The court noted that the trier of fact was not obligated to credit the defendant’s "good-citizen tale” of how he came to be drunk in the ditch. Cummings, 176 Ill. App. 3d at 297.
Relying on Cummings, defendant urges us to hold that intoxicated individuals who voluntarily choose to sleep off the effects of alcohol in a parked vehicle may do so without fear of prosecution. We are unpersuaded by Cummings’ reasoning and defendant’s argument. The term "actual physical control” in section 11 — 501 is unqualified by any language suggesting that the accused’s purpose in occupying a vehicle is germane to criminal responsibility. Courts in other jurisdictions have emphasized the preventive nature of statutes proscribing actual physical control by those under the influence of alcohol. It has been stated that the purpose of such statutes is to discourage intoxicated persons from entering motor vehicles except as passengers. In re Suspension of the Driver’s License of Vogt, 117 Idaho 545, 546, 789 P.2d 1136, 1137 (1990); Buck v. North Dakota State Highway Commissioner, 425 N.W.2d 370, 373 (N.D. 1988). "An intoxicated individual who gets into his vehicle to sleep poses a threat of immediate operation of his vehicle at any time while still intoxicated.” Buck, 425 N.W.2d at 373; see also Stevenson v. City of Falls Church, 243 Va. 434, 440, 416 S.E.2d 435, 439 (1992) (Compton, J., dissenting, joined by Carrico and Hassell, JJ.) ("Ordinary experience tells us that one in a drunken *405stupor in the driver’s seat of a vehicle is likely to arouse abruptly, engage the motive power of the vehicle, and roar away imperiling the lives of innocent citizens”). In State v. Lawrence, 849 S.W.2d 761 (Tenn. 1993), the court stated:
"We agree with the observation that '[a] motor vehicle is recognized in the law as a dangerous instrumentality when in the control of a sober person; in the control of a drunk, the dangerous instrumentality becomes lethal. Therefore *** the court [should interpret] the drunk driving statute in a way that [keeps] drunks from behind the steering wheels of motor vehicles, even when the drunk need[s] to "sleep it off.” ’ ” Lawrence, 849 S.W.2d at 765, quoting Stevenson v. City of Falls Church, 243 Va. 434, 440, 416 S.E.2d 435, 439 (1992) (Compton, J., dissenting, joined by Carrico and Hassell, JJ.).
The legislature’s use of the broad, unqualified phrase "actual physical control” in section 11 — 501 reflects a legislative public policy of encouraging those who plan to drink at a party or tavern to arrange lodging or safe transportation home before they set out. A person may embark upon an evening of drinking with the intention of sleeping in his or her car, but the actual decision whether to do so will be made at a time when the person’s judgment is impaired by alcohol. While some courts have embraced a construction of "actual physical control” permitting the use of a vehicle for stationary shelter (see, e.g., State v. Holloran, 669 A.2d 800, 801 (N.H. 1995); Atkinson v. State, 331 Md. 199, 216, 627 A.2d 1019, 1027 (1993)), for the reasons set forth above, we decline to adopt such a construction.
The evidence in the case at bar is sufficient to support the jury’s determination that defendant was in actual physical control of his vehicle. It is no defense that defendant may have intended only to use the vehicle for shelter while achieving sobriety.
Defendant also argues that the trial court committed reversible error by excluding evidence relevant to *406the defense of necessity and by refusing to instruct the jury on that defense theory. We need not address the argument, as it is waived. Supreme Court Rule 315(b)(3) states that a petition for leave to appeal shall contain "a statement of the points relied upon for reversal of the judgment of the Appellate Court.” 155 Ill. 2d R. 315(b)(3). Rule 315(b)(5) states that the petition shall contain "a short argument *** stating *** why the decision of the Appellate Court should be reversed or modified.” 155 Ill. 2d R. 315(b)(5). In the case at bar, the "points relied on for reversal” and "argument” sections of defendant’s petition for leave to appeal focused exclusively on the question of whether defendant was shown to be in actual physical control of his vehicle; defendant did not raise any issue involving the defense of necessity. A party’s failure to raise an argument in the petition for leave to appeal may be deemed a waiver of that argument. Federal Deposit Insurance Corp. v. O’Malley, 163 Ill. 2d 130, 154 (1994). We therefore decline to address defendant’s argument regarding the defense of necessity.
CONCLUSION
For the foregoing reasons, the judgment of the appellate court is affirmed.
Affirmed.