(a) Definition of attempt.— A person commits an attempt when, with intent to commit a specific crime, he does any act which constitutes a substantial step toward the commission of that crime.
(b) Impossibility.–It shall not be a defense to a charge of attempt that because of a misapprehension of the circumstances it would have been impossible for the accused to commit the crime attempted.
(1) In any prosecution for an attempt to commit a crime, it is a defense that, under circumstances manifesting a voluntary and complete renunciation of his criminal intent, the defendant avoided the commission of the crime attempted by abandoning his criminal effort and, if the mere abandonment was insufficient to accomplish such avoidance, by taking further and affirmative steps which prevented the commission thereof.
(2) A renunciation is not “voluntary and complete” within the meaning of this subsection if it is motivated in whole or part by:
(i) a belief that circumstances exist which increase the probability of detection or apprehension of the defendant or another participant in the criminal enterprise, or which render more difficult the accomplishment of the criminal purpose; or
(ii) a decision to postpone the criminal conduct until another time or to transfer the criminal effort to another victim or another but similar objective.
1972, Dec. 6, P.L. 1482, No. 334, § 1, effective June 6, 1973.
As to grading of inchoate offenses, see § 905(a):
(a) Grading.— Except as otherwise provided in this title, attempt, solicitation and conspiracy are crimes of the same grade and degree as the most serious offense which is attempted or solicited or is an object of the conspiracy.
From the Guidelines Manual:
§ 303.3. Offense Gravity Score – general
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(c) Inchoate offenses. Inchoate offenses are scored as follows:
(1) Convictions for attempt, solicitation, or conspiracy to commit a Felony 1 offense receive an Offense Gravity Score of one point less than the offense attempted, solicited, or which was the object of the conspiracy.
(2) Convictions for attempt, solicitation, or conspiracy to commit any offense which is not a Felony 1 offense, receive the Offense Gravity Score of the offense attempted, solicited, or which was the object of the conspiracy.
(3) Convictions for attempt, solicitation, or conspiracy to commit any offense under The Controlled Substance, Drug, Device and Cosmetic Act (35 P.S. §780-101 — §780-144) receive the Offense Gravity Score of the offense attempted, solicited, or which was the object of the conspiracy.
(4) Exception for inchoate murder convictions. Convictions for attempt, solicitation, or conspiracy to commit murder receive the Offense Gravity Score of 14 if there is serious bodily injury and 13 if there is no serious bodily injury.
Maximum Penalty for inchoate murder:
– with serious bodily injury: 20-40 years
– without serious bodily injury: 10-20 years.