In the United States, each state and the federal government has its own system for classifying crimes under its own legal code. However in most instances, crimes are generally broken down along similar lines.

The first classification is between misdemeanors and felonies. Felonies are more serious offenses that are punishable by incarceration in the state penitentiary for more than one year, or for very serious felonies, death.

Misdemeanors are less serious crimes that are punishable by incarceration of less than one year in the county jail.

Within the two categories of felonies and misdemeanors, crimes are further broken down by the severity of the crime.

For example, a Class A misdemeanor is the most serious type of misdemeanor, and is punishable by a jail term not to exceed one year and a fine of a certain amount that varies from state to state.

Class B misdemeanors vary widely, but generally they are not punishable with jail terms that exceed 180 days.

Class C misdemeanors are generally not given jail terms but instead carry fines.

In the felony category, the most serious crimes, such as first-degree murder, are called capital felonies. Capital felonies, in jurisdictions that have the death penalty can carry with them the penalty of death or life in prison.

First-degree felonies are punishable with prison terms ranging from not less than five years to life.

Second-degree felonies are punishable by imprisonment of not more than 20 years and not less than 2 years.

Third degree felonies are punishable by imprisonment of not more than 10 years and not less than 2 years.

The obvious question arises, what determines whether a particular crime fits one category or another? The answer is a combination of the state law forbidding such crimes, previous offenses and mitigating or aggravating factors.

The penal code of that jurisdiction for example may classify causing the death of another into various types of crimes depending upon whether there was premeditation or whether the death was caused in the heat of passion. Theft and robbery may be classified depending upon the amount stolen and whether deadly weapons were used in the commission of the crime.

The defendant's criminal defense lawyer may present such factors that may mitigate the severity of the crime by showing things like a horrible childhood characterized by abuse and neglect, for example. If these factors are accepted, the crime might be lessoned or moved down from a higher class to a lower class.

Other mitigating factors could be to show that the victim had previously caused harm to the defendant, that the defendant's judgment was impaired through no fault of his own, or that defendant's actions were completely outside her normal personality (this is what is attempted when the defense presents character witnesses to show that the defendant was normally a peaceful and law abiding citizen).

On the other hand, the prosecution may present evidence to show aggravating factors, which could increase or move the crime up a class. Such aggravating factors might be to show that the victim was a minor, that the defendant used a deadly weapon in the commission of the crime, that the defendant intended to commit sexual assault along with the robbery, or that the defendant's actions were particularly heinous or depraved.

The defendant's previous criminal history is also taken into account. A first time offender may receive a lower classification, whereas a habitual criminal convicted of the same crime, may receive a more severe sentence as a result of having his crime classified as a more serious offense.