Arson 1 and Arson 2

Arson 1

Under the first theory of arson, the Commonwealth must prove three elements beyond a reasonable doubt:

A Defendant Caused a Building to be Burned.
The first element the Commonwealth must prove beyond a reasonable doubt is that the defendant set fire to, burned or caused to be burned the building in question. This equires that some portion of the building must have actually been on fire and burned.
That the Building was or was Joined to a Dwelling House
The second element the Commonwealth must prove beyond a reasonable doubt is that the building burned was a dwelling house, a building adjoining or adjacent to a dwelling house, or any building the burning of which results in a dwelling house being burned. The phrase "dwelling house" means and includes "all buildings used as dwellings, such as apartment houses, tenement houses, hotels, boarding houses, dormitories, hospitals, institutions, sanitoria, or other buildings" where people live or reside.

The Commonwealth must prove that the building is capable of being occupied as a dwelling, is adjoining or adjacent to a dwelling house, or is a building the burning of which results in a dwelling house being burned. Further, it does not matter if the defendant owned the dwelling house or if it was owned by another.

A Defendant Acted Willfully and Maliciously.
The third element the Commonwealth must prove beyond a reasonable doubt is that the defendant willfully and maliciously set fire to or caused the building to be burned.

Willfulness and malice are required to constitute the state of mind necessary to commit arson. The word willfully means that the act was intentional and by design, rather than an act that is thoughtless or accidental. A person acting willfully intends both his or her conduct and the resulting harm. The requirement of willfulness means that accidentally or negligently caused burnings are not arson.

The Commonwealth also must prove beyond a reasonable doubt that the defendant acted maliciously or with malice. The terms of "malice" and "maliciously" have a different meaning under this statute than the ordinary definition of those terms. Malice characterizes all acts done with an evil disposition, with a wrong and unlawful motive or purpose or the willful doing of an injurious act without lawful excuse. A burning is malicious if it is done with any wrongful or unlawful motive or purpose and without lawful excuse.

Arson 2

If the Commonwealth fails to prove beyond a reasonable doubt that a defendant is guilty of arson under the first theory of arson, then you could be considered guilty under the second theory of arson. In order to prove the defendant guilty under the second theory of arson the Commonwealth must prove beyond a reasonable doubt:

In order to prove this element of arson, it is not sufficient for the Commonwealth to prove that the defendant merely knew that a crime was going to be committed. Mere association with the person who set the fire is not enough. Mere presence at the scene of the crime is not enough, even when combined with knowledge of the planned act. A mere failure to take appropriate steps to prevent the commission of the crime or mere acquiescence is not sufficient.

Intentionally Aided, Counseled or Procured
The Commonwealth must prove that a defendant aided, counseled or procured the burning of a dwelling house or building. This means that the defendant participated in committing the crime of arson by agreeing to stand by, at, or near the scene of the crime to render aid, assistance or encouragement, if it became necessary, to the person who set fire to or caused the burning of the dwelling house; or by assisting the perpetrator to make an escape from the scene; or by procuring another person to burn a dwelling house.
A Burning
The Commonwealth must prove that a burning occurred. This requires that some portion of the building must have actually been on fire and burned.
That the Building was (or was joined to), a dwelling House
The Commonwealth must prove that the building burned was a dwelling house, a building adjoining or adjacent to dwelling house, or a building whose burning resulted in a dwelling house being burned. The phrase "dwelling house" means and includes "all buildings used as dwellings, such as apartment houses, tenement houses, hotels, boarding houses, dormitories, hospitals, institutions, sanitoria, or other buildings" where people live or reside