A systematic review evaluated the impact of 34 electronic monitoring programs for offenders on recidivism. According to the findings, electronic monitoring produces positive effects for certain offenders (such as sex offenders) at certain points in the criminal justice process (post-trial rather than incarceration), and perhaps in combination with other conditions and therapeutic components. However, evidence suggests that electronic monitoring is less effective to reduce recidivism for other subgroups of offenders (no statistically significant effects have been found in high-risk offenders) [1].
That said, in studies that utilize hazard rates, the overall effect of electronic monitoring on recidivism was statistically significant in the direction of a crime reduction effect. Thus, it can be said that, overall, the evidence of the impact of electronic monitoring on recidivism is mixed, as the estimate of effectiveness varies depending on the form of measurement used. A statistical impact on recidivism is observed when it is measured based on the risk rate, but not when it is measured in proportions, mainly due to the heterogeneity of the studies.
According to a second systematic review, there are no statistically significant effects on recidivism resulting from electronic monitoring for moderate and serious offenders. Only two studies were identified in which effects were observed in small subpopulations of offenders: individuals on parole for sexual offenses and individuals released from prison. However, in these two cases the monitoring programs were associated with reintegration techniques such as Cognitive Behavioral Therapy. [2]
The authors of a third review located nine studies on electronic monitoring and also concluded that these programs do not, on average, have a statistically significant effect on recidivism rates. However, the authors note that electronic monitoring programs are typically used to mitigate costs related to the prison and criminal justice systems, and are not always explicitly intended to impact recidivism specifically. In this area, benefits of adopting the practice were found, given that the average cost of electronic monitoring programs is equivalent to US$1,236 per prisoner, while in the closed regime an average of US$2,107 per offender was observed [3].