Trying youths as adults

Impact on crime
Evidence quality 1
How it works
cog full Evidence quality 1
Where it works
where full Evidence quality 1
How to do it
what full Evidence quality 2
What it costs
cost empty Evidence quality 0
Economic cost

What is the focus of the intervention?

Many developed countries have a separate criminal justice system for youths under 18 years old (also known as minors or juveniles).  These were created in the belief that youths are at a different stage of biological development and may be more amenable to rehabilitation than adults. Juveniles are also arguably less aware of consequences and less responsible for their actions, and have less ability to understand the adult judicial process and participate in it.

Under certain circumstances – usually, relating to severity of offending – youths may be transferred following arrest, from the youth justice system to the jurisdiction of the adult criminal justice system.

The focus of this overview is on the prevention of violent crime through such transfers, although some studies included other types of crime outcomes.

This narrative is based on one systematic review including a meta-analysis of 9 studies.  All studies in the review come from the United States. 


How effective is it?

Overall, the evidence suggests that the intervention has increased crime.

Transferred youths were approximately 33.7% more likely in the following 18 months to 2 years to be re-arrested for a violent or other serious crime than offenders retained in the youth criminal justice system (based on 5 studies).  This analysis was based on the concept of specific deterrence (see mechanism section below). 

Three studies examined the effect of general deterrence but the findings were inconsistent, and the review concluded that there was insufficient evidence to determine an effect on the wider youth offending population.

How strong is the evidence?

Although the review was systematic, many forms of bias that could influence the study conclusions remain. 

This evidence is taken from a systematic review covering 9 studies, which had a transparent and well-designed search strategy.  It did not, however, analyse all potential issues which could affect the outcomes of the statistical analysis, sufficiently assess the risk of bias from published or unpublished studies or conduct separate analyses for distinct evaluation research designs.

One potential bias that was present in the primary studies on which this review is based is that of selection bias.  This relates to the fact that transfer to the adult criminal justice system is generally intended for more serious youth offenders, who may be expected to have a greater risk of subsequent violence.  This may not always occur in practice though.

To try and control for this, study authors generally restricted crimes included within the studies to serious crimes, which could then be compared to any violent outcomes of juveniles who were transferred.


How does it work?

This intervention is believed to work through mechanisms of deterrence and incapacitation. 

Youth transfers could work through general or specific deterrence. General deterrence refers to how the perceived likelihood and severity of a transfer could deter all young people in the population from offending.

Specific deterrence refers to how transfers might deter young offenders who have been processed through the adult system from re-offending.

If youths in adult custodial settings serve longer sentences than they would serve under the youth system, then reductions in violence by transferred youths might also be achieved through the mechanism of incapacitation.  That is, whilst in custodial settings they would be unable to commit violent crimes in the community. 

The review notes that both the deterrence and incapacitation mechanisms depend on the assumption that more severe sentences are associated with the adult criminal justice system, compared with the youth system. 

Although discussed, none of these potential mechanisms are tested in the review.


In which contexts does it work best?

The review notes that the effect of the intervention might differ for youths that are arrested for more and less serious offences. 

One study examined this and found that re-arrest rates were higher, but not significantly so, for transferred youth who committed misdemeanours (less serious offences) when compared to youths retained in the youth justice system.  In contrast, the same study found that the re-arrest rates for youths arrested for property felonies (more serious offences) were slightly lower for transferred than for retained offenders.  These results were highly specific to the legal system in this study area in Florida, and in other places offenders committing less serious offences would not be eligible to be transferred to the adult criminal justice system.

The review notes that the geographical and demographic diversity in the range of US states covered by the primary studies suggests that the findings may be broadly applicable elsewhere.


What can be said about implementing this initiative?

The review states that for a juvenile to be transferred to adult court jurisdiction they must be individually determined for selection, or must be deemed to be unreceptive to treatment. There are six main ways in which youths can be transferred to the adult criminal justice system across the diverse states in the US: 

  1. In a ‘judicial waiver’ a youth court judge may waive a youth to the adult system, generally based on perceived lack of amenability to treatment, which in turn is often based on considerations such as age, seriousness of the current offence, and prior offending history.
  2. In a ‘prosecutorial waiver’ the prosecutor has the discretion to file a case in the youth or the adult criminal court system.
  3. In a ‘statutory exclusion’ youths of particular ages charged with particular crimes are excluded from the youth justice system.  Discretion then reverts to prosecutors who decide which charges are filed.
  4. Once the youth is transferred to an adult court (through one of the first three ways) they then remain in the adult criminal justice system for any subsequent offending.
  5. States can set the age at which an offender is responsible for their criminal actions lower than the traditional age of 18 years.
  6. In many states, juvenile who are married or otherwise not living with parents are excluded from the youth court. If the cases are considered inappropriate for the adult court system then the authority exists to transfer them back to the youth court.  This is generally referred to as ‘reverse waiver’.


How much might it cost?

The review does not mention costs (and/or benefits) and no formal economic analysis is provided. 

The review authors noted that information on costs would be useful, even though full cost evaluation might be unnecessary for interventions that cause net harm.

General considerations

  • It is unclear whether the effect of increased re-offending (as seen in the studies covered by this review) is attributable to the overall judicial process, the differences in sanctions experienced by the youths or to some other component of the process.
  • The review notes that the transfer of youth to the adult justice system may be associated with increases in the young offenders’ victimisation during their incarceration.  Similarly, rates of inmate suicide among incarcerated youths may differ between those in youth and adult custodial settings.


Overall, the evidence suggests that the intervention has increased crime.  Therefore transferring youths to the adult justice system is considered counterproductive as a strategy for reducing reoffending.

The evidence is however weak, and is restricted to US studies.  There is insufficient evidence to determine whether the intervention has a consistent impact on general deterrence for the wider youth offending population.

Ratings for Individual Reviews

Review 1

How it works
cog full Evidence quality 1
Where it works
where full Evidence quality 1
How to do it
what full Evidence quality 2
What it costs
cost empty Evidence quality 0
Economic cost


Review 1: McGowan, A., Hahn, R., Liberman, A., Crosby, A., Fullilove, M., Johnson, R., Moscicki, E., Price, L., Snyder, S., Tuma, F., Lowry, J., Briss, P., Cory, S. and Stone, G. (2007). Effects on Violence of Laws and Policies Facilitating the Transfer of Juveniles from the Juvenile Justice System to the Adult Justice System. American Journal of Preventive Medicine. 32(4S), pp. S7-S28.

This narrative was prepared by UCL Jill Dando Institute and was co-funded by the College of Policing and the Economic and Social Research Council (ESRC).  ESRC Grant title: 'University Consortium for Evidence-Based Crime Reduction'.  Grant Ref: ES/L007223/1.

Uploaded 28/07/15

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