Additionally, one crime may have a variety of participants and each may be involved to a different
degree. A thorough understanding of criminal law will enable the investigator to determine the
respective liability of these various participants.
Depending upon the facts of a particular case, certain legal defenses to the crime under investigation
may be available. Recognizing the applicability or nonapplicability of an affirmative defense will
enable the investigator to recognize and record the facts critical to either proving or disproving the
defense. Unless these potential defenses are recognized, critical facts may well be lost to the
prosecution as well as to the defense.
PART A - THE ELEMENTS OF A CRIME
A crime is an offense against society, a social harm that is defined and made punishable by law. Just as
an army exists to protect a society against external enemies, the criminal law and its agencies (police,
courts, and correctional facilities) exist to protect society against its internal enemies. Crime is an attack
upon society and the criminal law seeks to identify, prescribe, punish, and deter such attacks.
A crime generally consists of two basic parts: A physical element (the criminal act) and the mental
element (the criminal intent).
A. Criminal Act. The difference between the average law-abiding citizen and the criminal is not
that the citizen has never possessed the intent to commit a crime. Rather, it is that the law-abiding
citizen does not permit this state of mind to rule his conduct.
There can be no crime without an act. Intent alone, no matter how wrongful, is not punishable and our
law will not recognize intent alone as a crime. Only when such an intent is coupled with a criminal act
will society recognize that a crime has been committed. If PVT Smith intends to kill someone, this
intent in itself does not constitute a crime. Before PVT Smith can be held criminally liable, he must go
beyond mere thoughts and actually commit an act toward the completion of his intended crime.
Society's refusal to punish mere thoughts has its roots in traditional fears of "thought control" as well as
in a recognition of the near impossibility of proof and enforcement.
B. Criminal Intent.
Most crimes require that the person who commits the crime have criminal intent. This principle
flows from the idea that society does not usually punish accidental violations of the law. This is the
general rule. There are exceptions. One is where the accused didn't intend to commit any crime, but
was guilty of "criminal" negligence. An example of this is involuntary manslaughter. Here, the
accused's gross negligence is essentially equivalent to that intent. Another example is carnal knowledge,
where the accused's intent is immaterial. We'll return to these later.