In addition to "three strikes" laws, other state and all federal criminal statutes include mandatory sentences that require judges to impose identical sentences on all persons convicted of the same offense. Mandatory sentences are a direct result of state legislatures' or Congress' response to the public perception of judicial leniency or inconsistency in sentencing practices.

However, most crimes do not carry mandatory sentences. If sentencing is not mandatory, judges may "fit the punishment to the offender" rather than "fit the punishment to the crime." Competing theories about criminal justice help to fuel the different approaches to sentencing and punishment. These include the severity of punishment meted, and the specific objective sought by the punishment:

• Retribution. Some believe that the primary purpose of punishment should be to punish an offender for the wrong committed, society's vengeance against a criminal. The sentiment is to punish criminals and promote public safety by keeping them "off the streets."

• Rehabilitation. Others believe that the primary purpose of punishment should be to rehabilitate criminals to mend their criminal ways and to encourage the adoption of a more socially acceptable lifestyle. Most experts agree that this theory is commendable but not practical in prisons. Many criminals boast of coming out "better criminals" than they were when they entered prison.

• Deterrence. Still others argue that the perceived punishment for a crime should be so undesirable as to result in deterring someone from actually committing a crime for fear of the likely punishment. Again, the theory is commendable, but many crimes are committed on impulse or under the influence of alcohol and other drugs. Fear of punishment is usually not a deterrent under these circumstances. Moreover, repeat offenders do not fear incarceration the way that people who have been free all their lives might.