Mandatory minimum sentencing can be designed to avoid injustices.  The negative side effects of minimum sentencing guidelines can be avoided via “safety valves.” The U.S. federal government introduced safety valves in 1994; mandatory sentencing is suspended if the defendant meets certain criteria, such as being a low-level participant or having no prior criminal history. The safety valve allows flexibility so that low-risk offenders do not receive excessively harsh punishment. Thus mandatory sentencing guidelines have enough flexibility to recognize varying circumstances, while retaining enough rigidity to deliver consistent punishment.