In this case the defendant appeals from a conviction of aggravated arson, a second degree felony. In a statement to the police, the defendant admitted setting a house on fire, but claimed that he was acting under the direction of the owner of the house. In his appeal the defendant claims that under U.C.A., 1953, § 76-6-103 the owner could not have been convicted of aggravated arson for setting fire to his own home. Therefore, the defendant argues that he should not have been convicted of aggravated arson because he was acting as the owner’s agent. We disagree and affirm the conviction.
The defendant’s argument depends upon his assertion that an owner who sets fire to his own house cannot be convicted of aggravated arson. The statute reads as follows:
Aggravated arson. — (1) A person is guilty of aggravated arson if by means of fire or explosives he intentionally and unlawfully damages:
(a) A habitable structure; or
(b) Any structure or vehicle when any person not a participant in the offense is in the structure or vehicle.
(2) Aggravated arson is a felony of the second degree.
U.C.A., 1953, § 76-6-t103 (1978 edition). The defendant points out that at common law it was not unlawful to burn one’s own dwelling. See, e.g., 5 Am.Jur.2d Arson § 23 (1962); Annot., 17 A.L.R. 1168 (1922). The provisions of the Utah Criminal Code, however, supersede the common law. U.C.A., 1953, § 76-1-105 (1978 edition). The statute regarding aggravated arson is one of three sections that deal with arson. The previous section defines arson:
(1) A person is guilty of arson, if, under circumstances not amounting to aggravated arson, by means of fire or explosives, he unlawfully and intentionally damages:
(a) Any property with intention of defrauding an insurer; or
(b) The property of another.
(2) A violation of subsection (a) is a felony of the third degree. A violation of subsection (b) is a felony of the third degree if the damage caused exceeds $5,000 value; a class A misdemeanor if the damage exceeds $1,000 but is not more than $5,000 value; a class B misdemeanor if the damage caused exceeds $250 but is not more than $1,000; any other violation is a class C misdemeanor.
U.C.A., 1953, § 76-6-102 (1978 edition). Reckless burning is also defined:
(1) A person is guilty of reckless burning if he:
(a) Recklessly starts a fire or causes an explosion which endangers human life; or
(b) Having started a fire, whether recklessly or not, and knowing that it is spreading and will endanger the life or property of another, either fails to take reasonable measures to put out or control the fire or fails to give a prompt fire alarm; or
(c) Damages the property of another by reckless use of fire or causing an explosion.
(2) A violation of subsections (a) and (b) is a class A misdemeanor. A violation of subsection (c) is a class A misdemeanor if damage to property exceeds $1,000 value; a class B misdemeanor if the damage *640to property exceeds $500 value; and a class C misdemeanor if the damage to property exceeds $50 value. Any other violation under subsection (c) shall constitute an infraction.
U.C.A., 1953, § 76-6-104 (1978 edition). Both the arson and reckless burning statutes distinguish “the property of another” from other types of property. The aggravated arson statute makes no reference to ownership of property in proscribing damage by fire to “a habitable structure” or “any structure or vehicle” when it is occupied. Nevertheless, the defendant contends that the statute should be construed as if it read “the habitable structure of another.” The defendant points to the word “unlawfully” in the statute and argues that the arson statute, § 76-6-102, defines what conduct is unlawful. Thus, the defendant incorporates the provisions of § 76-6-102, Arson, into § 76-6-103, Aggravated Arson, claiming that aggravated arson is simply arson, i.e., damage with the intent to defraud or to damage the property of another, when the property is habitable or occupied. The defendant cites no case law or legislative history to support this construction of the statute. Neither does the defendant explain why “unlawfully” in the arson statute should be internally defined, but the same word in the aggravated arson statute should be defined by the provisions of the arson statute. The defendant’s only justification for this construction is that it preserves the common law concept of arson. However, a review of the statutes which preceded the current code indicates that our legislature did not intend to exclude the burning of one’s own property from the statutes.
Under Utah’s earliest statutes, as under the common law, arson was a crime against possession rather than ownership of property-
To constitute arson it is not necessary that a person other than the accused should have had ownership in the building set on fire. It is sufficient that at the time of the burning another person was rightfully in possession of, or was actually occupying such building or any part thereof.
Compiled Laws of Utah, § 119-40-8253 (1917). Arson was defined as “the wilful and malicious burning of a building with intent to destroy it.” Compiled Laws of Utah § 119-40-8248 (1917). “Maliciously burning in the night time an inhabited building in which there is, at the time, some human being, is arson in the first degree; all other kinds of arson are of the second degree.” Compiled Laws of Utah, § 119-40-8254 (1917). Thus, even when the Utah statute closely followed the common law, ownership of the property was a secondary consideration. The primary concern was for danger to human life.
In 1931, the Utah legislature enacted new statutes that classified arson as first, second and third degree arson according to the likelihood of danger to human life. Rather than attempt a general definition of when and under what circumstances lives might be endangered by burning structures, this statutory scheme distinguished the three degrees of the offense by specifying the particular property burned. First degree arson was the willful and malicious burning of a dwelling or any other building “that is parcel thereof, or belonging to or adjoining thereto, whether the property of himself or of another.” U.C.A., 1943, § 103-6-1 (emphasis added). Second degree arson was even more explicit in penalizing the willful and malicious burning of “any church, meetinghouse, courthouse, school, jail or other public building, or any public bridge” as well as “any bam, stable, garage or other building, whether the property of himself or of another, not a parcel of a dwelling house; or any shop, storehouse, warehouse, factory, mill or other building, whether the property of himself or another.” U.C.A., 1943, § 103-6-2 (emphasis added). Section 103-6-3, third degree arson, dealt with the willful and malicious burning of various structures not considered to be buildings, crops in storage or in the field, piles of fuel or building materials, and various types of vehicles. The application of this statute, however, is specifically limited to property worth $25 or more that is the property of *641another. In summary, it is apparent that the most severe penalty was intended to reach those who burned structures likely to be occupied, regardless of ownership or actual occupancy, while the least severe penalty was imposed for damage to various kinds of personal property belonging to another.
This scheme was used in the Model Arson Law proposed by the National Board of Fire Underwriters in 1953. See Model Penal Code § 220.1 comment 1 at n. 15 (1980). However, a system of classification by type of property has a number of weaknesses.
For example, the burning of an empty, isolated dwelling could lead to a 20-year sentence, while setting fire to a crowded church, theater, or jail was a lesser offense with a 10-year maximum. The destruction of a dam, factory, or public service facility was regarded as less serious than destruction of a private garage on the grounds of a suburban home. It also makes little sense to treat the burning of miscellaneous personal property, whether out of malice or to defraud insurers, as a special category of crime apart from the risks associated with burning. To destroy a valuable painting or manuscript by burning it in a hearth or furnace cannot be distinguished eriminologically from any other method of property destruction. Moreover, the treatment of attempt as the same two-year felony no matter what the nature of the crime attempted seriously undercuts the grading scheme.
Id. at 8-9. In 1973, the Utah legislature revised the Criminal Code. By referring explicitly to “habitable structures” and the actual presence of a person, the current arson statutes preserve the classification of the offense according to degree of danger to human life while eliminating many of the inconsistencies associated with the previous method. The most severe penalty is still intended to reach those who burn structures likely to be occupied, regardless of ownership or actual occupancy. The absence of the words “property of another” from the aggravated arson statute is entirely consistent with the legislature’s earlier treatment of the offense. There is no reason to assume that the omission of those words was inadvertent. Neither is there any necessity for contriving a definition of “unlawfully” in order to superimpose common law notions on the plain words of the statute. A fire poses unique hazards. As a means of destruction, it is difficult to control and may quickly spread to nearby buildings or fields. Firemen and policemen are endangered. Neighbors and passers-by, fearing that a structure is occupied, may attempt hazardous rescue efforts. It is the apparent intent of the legislature that persons who create these risks should suffer a heavy penalty.
This is not to say that the statute absolutely prohibits an owner from setting fire to his own property. Section 76-6-103 states that the person is guilty only if he acted “intentionally and unlawfully.” “A person engages in conduct: (1) Intentionally .. . when it is his conscious objective or desire to engage in the conduct or cause the result.” U.C.A., 1953, § 76-2-103(1) (1978 edition). Thus, the person who carelessly burns a pile of trash in a high wind, setting fire to his own home or another’s, might be found guilty under the reckless burning statute, but could not be found guilty of aggravated arson. Similarly, a homeowner who accidentally sets fire to his garage with his welding torch could not be said to have “intentionally” damaged a habitable structure. The word “unlawfully” also limits the reach of the aggravated arson statute. Although the term is not defined by statute, it appears often in the Criminal Code meaning without justification, license or privilege. See, e.g., U.C.A., 1953, § 76-6-201(3) (1978 edition). Many municipalities have fire safety regulations. See, e.g., Revised Ordinance of Salt Lake City, Utah § 15-1-10, et seq. (1974). If a property owner complied with such regulations, obtained any necessary permit, notified the fire department, warned the neighbors, obtained assistance in organizing safety precautions, or assured an adequate supply *642of water, an owner could demonstrate the lawful nature of his activity.1
The availability of such a defense does not, as the dissent argues, impermissi-bly shift to the defendant the burden of proof of an element of the crime of aggravated arson. The situation is analogous to the treatment of any affirmative defense such as self-defense in a prosecution for assault or homicide. The unlawfulness of a defendant’s actions, when they are prohibited by the criminal statute, may be shown by evidence of the actions themselves, unless and until evidence is offered by either party that raises the possibility of lawful justification for the acts. The State at all times continues to carry the burden of proving the absence of an affirmative defense or, as in this case, the unlawfulness of a burning of property. The dissenting opinion’s argument appears to rest in the end on the assumption that it is per se lawful (absent malice) to burn one’s own property under Utah law. We disagree and hold herein that the legislature may properly declare such a burning unlawful and that it has done so in our statute.
In the instant case the defendant, who was in possession of the house, and his friend apparently fired some shots in the kitchen very late one night. The friend then left, and the defendant apparently used a fire accellerant to set the house on fire. There is no suggestion that the fire was accidental or that there was any justifiable or beneficial purpose for the fire that occured at approximately 1:50 a.m. The defendant intentionally created the risk that neighbors, firefighters and policemen would be exposed to danger, all without any demonstrated justification or lawful purpose.
It may be felt that the imposition of the penalty for a second degree felony is too harsh when no person was actually in the structure or actually injured by the fire.2 However, the decision to extend broad protection to all habitable structures, in order to avoid the risk to human life posed by fire, is a policy decision that the legislature is competent to make. “It is the power and responsibility of the Legislature to enact laws to promote the public health, safety, morals and general welfare of society, and this Court will not substitute our judgment for that of the Legislature with regard to what best serves the public interest.” Bastian v. King, Utah, 661 P.2d 953, 956 (1983) (citation omitted). See also West Jordan v. Morrison, Utah, 656 P.2d 455 (1982).
The Utah legislature is not unique in including as part of its aggravated arson statute a presumption that any intentionally set fire in a habitable structure poses danger to human life. In Arizona, aggravated arson is also a second degree felony: “A person commits arson of an occupied structure by intentionally and unlawfully damaging an occupied structure by knowingly causing a fire or explosion.” Ariz.Rev.Stat.Ann. § 13-1704 (1982 Supp.). By definition, occupied structure “includes any dwelling house, whether occupied, unoccupied or vacant.” Ariz.Rev.Stat.Ann. § 13-1701(2) (1978). There are no Arizona cases that limit or alter the straightforward language of the statute. In Ohio, the aggravated arson statute includes both “substantial risk of serious physical harm to any person” and “physical harm to any occupied structure.” Ohio Rev.Code Ann. § 2909.02
*643(Page Supp.1982) (emphasis added). The Ohio definition of “occupied structure” is even broader than the Arizona definition, including not only dwellings but also any structure or vehicle occupied as a temporary or permanent habitation or adapted for overnight accommodation “whether or not any person is actually present.” Ohio Rev.Code Ann. § 2909.01 (Page 1982) (emphasis added). The Committee Comments following this definition emphasize that “[t]he definition’s general concept is that the actual or likely presence of a person in a structure, regardless of the nature of the structure itself, creates a more serious risk of harm from commission of arson ... and thus warrants more severe treatment of offenders.” In its comments following the definition of aggravated arson, the Ohio legislature expressed a rationale that could apply also to the Utah statute:
[T]he section represents a significant shift in emphasis from the way in which the relative severity of arson offenses was formerly determined, by using the degree of danger to persons as the key factor and placing only secondary reliance on the kind of property involved in the offense.
Ohio Rev.Code Ann. § 2909.02, Committee Comment (Page 1982). These statutes became effective in 1974. Research reveals no cases since then that construe these statutes to apply only to property of another or only when another person is actually present.
Other states have enacted similar legislation. The Minnesota first degree arson statute penalizes anyone who damages a building “used as a dwelling ... whether the inhabitant is present therein at the time of the act or not, or any building appurtenant to ... a dwelling whether the property of himself or of another.” Minn.Stat. § 609.561(1) (1982). Subdivision (2) of the statute applies the same penalty to one who burns any other type of structure when a person is actually present in the structure or “[t]he circumstances are such as to render the presence of such a person therein a reasonable possibility.” Minn.Stat. § 609.-561(2) (1982). The Minnesota statute is broader than the Utah statute in that the Utah statute presumes the reasonable possibility of the presence of another in any habitable dwelling, but requires the actual presence of a person in any other structure. There are no cases that alter or limit the application of the Minnesota statute. See also Del.Code Ann. tit. 11 § 803 (1979). The first degree arson statute in Connecticut similarly proscribes the burning of an inhabited building or any building that “the person has reason to believe ... may be inhabited” as well as intentional damage that actually injures a person. Conn.Gen. Stat. § 53a-111 (1983). The Connecticut statute also includes as first degree arson the circumstances when “at the scene of such fire or explosion a peace officer or firefighter is subjected to a substantial risk of bodily injury.” Conn.Gen.Stat. § 53a-111(a)(4) (1983) (emphasis added). The Utah statute presumes such a risk whenever a habitable structure is involved.
The Oregon legislature took a slightly different approach in 1971 when it defined first degree arson as damage to “protected property of another” or to “any property, whether his own or another’s, and such act recklessly places another person in danger of physical injury or protected property of another in danger of damage.” Or.Rev. Stat. § 164.325 (1981). Section 164.305(1) defines “protected property” as “any structure, place or thing customarily occupied by people, including ‘public buildings’ ... and ‘forest land’.” The Criminal Law Revision Commission commented:
The aim of the Commission is to protect human life and safety by enhancing the degree of arson to first degree when the property involved is a building, structure or thing of a kind which is typically occupied by people. The risk to human life or safety is especially great where such property is set afire .... The following guidelines are meant to aid in interpreting the phrase “customarily occupied by people” as it is used within the definition of “protected property” .... [A] building, structure or thing is customarily occupied by people if:
*644(a) By reason of circumstances of time and place when the fire or explosion occurs, people are normally in the building, structure or thing; or
(b) Circumstances are such as to make the fact of occupancy by persons a reasonable possibility.
Because it will normally be a jury question whether the state has proved that the building, structure, or thing is “customarily occupied,” the jury will be appropriately instructed that if they find it is customarily occupied the crime would be first degree arson ....
State v. Perez, Or.App., 13 Or.App. 288, 508 P.2d 833, 834 (1973) (quoting Criminal Law Revision Commission Final Draft of July, 1970) (upholding submission to jury of whether an unoccupied camper in a parking lot at 2:20 a.m. on a summer night was “customarily occupied by people” and affirming the first degree arson conviction). Thus, the Oregon statutes do not require actual occupancy, but do not presume, as do the Utah statutes, that damage by fire to any habitable structure creates a risk of danger to human life.
Still another approach is used in New York. The statutes defining first degree arson (explosions) and second degree arson (fire) specify guilt when a person intentionally damages a building when “(a) another person who is not a participant in the crime is present in such building at the time, and (b) the defendant knows that fact or the circumstances are such as to render the presence of such a person therein a reasonable possibility.” N.Y.Penal Law §§ 150.15, 150.20 (McKinney Supp.1982) (emphasis added). Thus, the aggravating element depends on neither the type of structure nor ownership of property, but rather on the defendant’s actual or constructive knowledge of the presence of another. See also N.Y.Penal Law § 150.15, note 1 (McKinney 1975) (listing older New York cases holding that “[ajrson in the first [now second] degree may be committed by one in burning his own dwelling-house.”) The New York third degree arson statute provides that “[a] person is guilty ... when he intentionally damages a building or motor vehicle by starting a fire or causing an explosion.” N.Y.Penal Law § 150.10 (McKinney Supp. 1982). The statute then sets out specific defenses:
In any prosecution under this section, it is an affirmative defense that (a) no person other than the defendant had a pos-sessory or proprietary interest in the building or motor vehicle, or if other persons had such interests, all of them consented to the defendant’s conduct, and (b) the defendant’s sole intent was to destroy or damage the building or motor vehicle for a lawful and proper purpose, and (c) the defendant had no reasonable ground to believe that his conduct might endanger the life or safety of another person or damage another building or motor vehicle.
Id. (emphasis added). The practice commentaries following this section note that “destruction by fire or explosives of one’s own building is only permitted under safe conditions and for a lawful purpose.” N.Y. Penal Law § 150.10 (McKinney 1975). Thus, the New York code limits the application of the first and second degree arson statutes by requiring the defendant’s actual or constructive knowledge of the presence of another, and limits the third degree arson statute by providing affirmative defenses based on the demonstration of safe and lawful conduct. See also Ala.Code §§ 13A-7-41 to -43 (1982); Del.Code Ann. tit. 11 §§ 802-804 (1979); Mo.Rev.Stat. §§ 569.040, -.050 (1978).3
*645In summary, it is clear that many states have shifted the emphasis in arson law from a system classifying the offense according to type or ownership of the building to a system based on probability of danger to human life. Some of these states, including Utah, have incorporated a presumption of danger to human life whenever a habitable structure is damaged by an intentionally set fire or explosion without inquiry into the actual intent or knowledge of the accused.4 We have held that it is the intent of the legislature to penalize more severely any person who intentionally damages by fire a habitable structure or structure actually occupied by a person, without regard for whether that structure is owned or possessed by the accused. We have also held that application of the aggravated arson statute is limited by the words “intentionally” and “unlawfully,” which require that the burning be other than accidental or careless and that the damage be without justification and contrary to safety precautions. Therefore, in the absence of evidence indicating accident or lawful purpose and safety measures, an owner of property may be convicted of aggravated arson for the burning of his own property under U.C.A., 1953, § 76-6-103 (1978 edition). The defendant’s argument that he cannot be convicted because he acted at the owner’s direction is without merit.
The defendant relies on State v. Christendon, 205 Kan. 28, 468 P.2d 153 (1970), in which the Kansas Supreme Court held that a defendant who set fire to a hotel at the owner’s request could not be convicted of first degree arson because the owner could not be convicted of first degree arson. This case is inapposite. The Kansas first degree arson statute clearly requires damage to “the property of another person.” Id. at 29, 468 P.2d at 155. We have held that the comparable Utah statute includes all habitable structures regardless of ownership.
The judgment of the trial court was correct, and we affirm.
OAKS and HOWE, JJ., concur.. The dissent argues that “unlawfully” is the equivalent of the word “maliciously,” which requires that “the burning be done to injure another in the house or the property of another in the house.” Section 103-6-1 of U.C.A., 1943, predecessor of the current aggravated arson statute, included the word “maliciously” as did the second degree arson statute. In 1973, the legislature deliberately omitted the term. The rest of the statute is consistent with this omission: (1) the “habitable structure” need not be occupied, U.C.A., 1953, § 76-6-101(2) (1978 edition), and (2) there is no requirement that the property be that of another. It is not the function of this Court to amend the legislature’s revision.
. The defendant was found guilty of aggravated arson, a second degree felony, but was sentenced to a third degree felony penalty under the provisions of U.C.A., 1953, § 76-3-402(1) (1978 edition). This statute allows the trial court to impose a sentence appropriate for the. next lower category of offense if the circumstances as a whole warrant.
. With the exception of the Delaware statutes (1953) and the New York statutes (1965, amended 1971, 1979), all the statutes referred to have been enacted since 1970. This is to be expected as most states have extensively revised their criminal codes within the last decade. The dissent relies on many older cases, some of which were written as early as mid-nineteenth century. These cases, which construe statutes since repealed and amended according to contemporary thought and policy, appear to be of limited utility in determining the intent of the Utah legislature in 1973. We note that statutory construction from another jurisdiction must always be secondary to the plain meaning of the statutes enacted in this *645jurisdiction. References to the arson statutes from other states are given here to indicate the wide variety of treatment of this offense even within those states with a similar approach.
. The same approach is found in U.C.A., 1953, § 76-6-203 (1978 edition), aggravated burglary, and § 76-6-302, aggravated robbery (1978 edition). In these statutes the presence of a deadly weapon or even a facsimile of a deadly weapon is sufficient to elevate the offense to a first degree felony without evidence of the actual intent or knowledge of the accused. The return to this “strict liability” approach in the arson statutes when there is a high risk of danger to human life is reminiscent of the early common law pattern of manifest criminality. See G. Fletcher, Rethinking Criminal Law §§ 2.2, 3.2.3, 3.2.4 (1978).