Mandatory sentences are those sentences which a judicial officer is required to impose regardless of the circumstances of the offense. In other words, the judicial officer has no discretion to impose a higher or lower sentence depending upon the nature of the crime. Typically, people convicted of certain crimes must be punished with at least a minimum number of years in prison. Among other arguments, advocates claim that mandatory sentences will deter criminals, while opponents claim it is unfair leads to prison overcrowding. Mandatory sentencing laws vary by federal and state laws.