A statute of limitation is a law which forbids prosecutors from charging someone with a crime that was committed more than a specified number of years ago. The general purpose of statutes of limitation is to make sure convictions occur only upon evidence (physical or eyewitness) that has not deteriorated with time. After the period of the statute has run, the criminal is essentially free.
Statutes of limitation generally require the criminal to remain in the state, gainfully employed and visible, seeming to necessitate that the criminal remain “catchable.” If the authorities fail to discover a criminal living in the open within a specified amount of time, society has determined that at that point the criminal should be able to live free from the possibility of prosecution. It appears that this notion is born out of a sense of mercy more than pragmatics: if the criminal is a fugitive, out of the state in which the crime was committed or otherwise living in hiding, this tolls, or suspends, the statute. (Once the criminal reenters the state the statute resumes running.) However, if the criminal were living an open, public, so-called “reformed” life, after a reasonable period of time he is allowed to be free from capture.
Not all crimes are governed by statutes of limitation. Murder, for example, has none. Sex offenses with minors, crimes of violence, kidnapping, arson, and forgery have no statutes of limitation in a number of states. In Arizona and California crimes involving public money or public records have no statutes of limitation. While in Colorado, treason has none.
Many states have adopted systems that classify felonies by category. Therefore, in order to effectively compare statutes of limitation provisions, it is necessary to determine which crimes in that state fit into particular classes. For example, Missouri lists murder or Class A felonies as crimes with no statutes of limitation. Each crime must then be looked up in that state’s statutes to determine its classification.