Ignition Interlocks As Alternatives to Hard Revocation for DWI Offenders Richard Roth, Paul Marques, Robert Voas Pacific Institute For Research and Evaluation Funded by NHTSA and RWJ Roth Revocation Alternative Annecy

Roth Revocation Alternative Annecy Outline The recidivism of DWI offenders subject to 10 year hard revocation in NM, with and without interlocks The recidivism of DWI offenders arrested between 2003 and 2005, with and without interlocks The effect of the New Mexico Interlock License Act on interlock installation rates Conclusions This is what I plan to talk about in this presentation: First, a study of the reduction in recidivism of interlocked offenders subject to 10 year license revocation in New Mexico Then, a study of the reduction in recidivism for all DWI offenders for whom the option of legal driving with an interlock license was available in NM. Third the effect of the New Mexico Ignition Interlock License Act on interlock installation rates. And finally some conclusions. Roth Revocation Alternative Annecy

Persons with 3 DWI Convictions within 10 years Group Control Interlock Group Size 15,571 14,271 1300 Prior Arrests (average) 3.78 4.28 Prior Convictions (average) 3.33 3.75 Age (average) 36.1 years 35.8 years BAC < 0.16% 18.0% 22.1% BAC >= 0.16% 48.4% 41.7% Refused BAC Test 33.6% 36.2% Gender: Male, Female, Missing 89.1%,10.9% 88.5%,10.8% 0.6% In New Mexico, persons having 3 DWI convictions within a 10 year period are subject to a 10 year revocation of their driver’s license from the data of their last conviction. This slide is for researchers to compare the characteristics of the interlock group and the control group for this study of those subject to 10 year revocation in NM. Note that 1300 offenders subject to the 10 year revocation did install interlocks before the end of that sanction period. The characteristics were close enough to be easily adjusted for in a Cox multivariate proportional hazards regression analysis. But first of all, I calculated the simple DWI rearrest rate per year for each group. Roth Revocation Alternative Annecy

Roth Revocation Alternative Annecy Rates are normalized to “DWI re-arrests per year” 12.5% A 74% reductiion! 4.4% 3.3% This control group of multiple offenders had 12.5% of their members rearrested within 1 year of the last conviction of the 3 in the 10 year period. By comparison only 3.3% of the interlock group were rearrested per year while interlocks were installed. That’s a 74% reduction from the 12.5% rate of the comparison group. For the total time from installation of interlock to the end of the study period (June 30, 2005), 4.4% of the interlock group were rearrested per year. Note that for a fair comparison, all recidivism rates were normalized to a per year basis. Roth Revocation Alternative Annecy

Roth Revocation Alternative Annecy 22.5% 6.0% For a more sophisticated analysis, I plotted one-minus-survival graphs and did univariate and multivariate Cox proportional hazards regression analyses. This one-minus-survival graph shows the fraction of the control group and the interlock group that are rearrested as a function of time. Clearly a much smaller fraction of the interlocked group were rearrested at any time (measured after installation and before removal for the interlock group and measured after the 3rd conviction in 10 years for the control group). Roth Revocation Alternative Annecy

Roth Revocation Alternative Annecy Installed Interlocks vs Controls Cox Proportional Hazards Regression Analysis Interlock/Control (Univariate) Odds Ratio = 0.2685 Multivariate Odds Ratio P value 95% C.I. Age (per year) 0.9788 0.0000 0.975-0.983 Gender F/M 0.8445 0.0073 0.746-0.955 BAC High/Low 1.1605 0.0045 1.047-1.286 BAC Refused/Low 1.2200 0.0003 1.096-1.358 Arrest # 1.1461 1.106-1.188 Conviction # 0.9650 0.2406 0.909-1.024 Interlock/Control 0.2556 0.189-0.346 This slide shows the result of the Cox regression analyses for the period during which interlocks were actually installed. The simpler univariate analysis which ignores any differences in other variables between the two groups gives an a odds ratio of 0.2685 (p < 0.0001). The more sophisticated multivariate analysis which adjusts for the effect of age, gender, BAC, prior arrests, and prior convictions gives an almost identical result, 0.2556. So both all three analyses indicate that the interlock group has only 26% of the recidivism of the control group. Roth Revocation Alternative Annecy

Roth Revocation Alternative Annecy From Installation to End of Study Period The previous analysis was for the period during which interlocks were actually installed. This graph shows the recidivism of the interlock group from the time interlock was installed to the end of the study period, even if the interlock was removed before the end of the study period. Researchers will note that the hazards are proportional and fairly constant. The odds ratio that comes out of the Cox analyses is the average value of the ratio of the slopes of these curves. Roth Revocation Alternative Annecy

Roth Revocation Alternative Annecy During and After Interlock vs Controls Cox Proportional Hazards Analysis Univariate Analysis: IG/CG Odds Ratio = 0.4153 Multivariate Odds Ratio P value 95% Confid Age (per year) 0.9787 0.0000 0.975 - 0.983 Gender F/M 0.8412 0.0059 0.744 - 0.951 BAC High/Low 1.1700 0.0027 1.056 -1.297 BAC Refused/Low 1.2329 0.0001 1.108 - 1.372 Arrest # 1.1425 1.103 -1.184 Conviction # 0.9671 0.2688 0.911 - 1.026 Interlock/Control 0.3955 0.310 - 0.504 Here’s the summary of the Cox analyses for interlock recidivism during the entire study period, including the time after interlocks were removed. First of all the univariate analysis gives an odds ratio of 0.42 (p<0.0001). Next the multivariate analysis that adjusts for the values of age, gender, BAC, prior arrests, and prior convictions gives a similar result of 0.40 (p<0.0001). The recidivism of the interlock group is only 40% as large as that of the control group. Roth Revocation Alternative Annecy

Recidivism of 10 year ALR Cox Regression Proportional Hazards Regressions Univariate Multivariate While Interlocked vs Controls 0.27 0.26 During and after interlock vs Controls 0.42 0.40 This slide summarizes the results of the 4 Cox regressions, showing a 74% reduction during interlock installation and a 60 % reduction over the entire study period. Roth Revocation Alternative Annecy

Roth Revocation Alternative Annecy A study of offenders arrested or interlocked between 2003 and June, 2005. 5707 offenders installed interlocks 3036 of the 5707 removed their interlocks before end of study, June 30, 2005 38,105 persons were arrested for DWI but did not install interlocks Next I will report on a study of all of the offenders arrested or interlocked between 2003 and June, 2005. In that period 5707 persons arrested for DWI in New Mexico installed interlocks. Before the end of the study period, 53 % of the interlocked offenders, 3036 out of 5707, had removed their interlocks. The control group consisted of 38,105 persons who were arrested during the same period but did not install interlocks. Note that this study includes voluntary and mandatory installations of interlocks. Roth Revocation Alternative Annecy

90 Days was the minimum revocation time and the maximum jail time for first offenders Installed after 1/1/03 and removed before July 05 days For the 3036 who removed interlocks before the end of the study period, this slide shows the distribution of installation times. You can see big peaks at 90 days and 1 year. The revocation for first offenders who did not refuse the BAC test was 90 days and the revocation for all others was 1 year. Also some judges mandated 90 day installations for first offenders because of the 90 maximum jail term for first offenders. The average installation time was 7 months (213 days) and the median was less than 6 months. Roth Revocation Alternative Annecy

Roth Revocation Alternative Annecy This slide shows the fraction re-arrested for DWI while interlocks were installed compared to the control group. It’s obvious that the interlocked group has far less recidivism. Roth Revocation Alternative Annecy

Cox Regression Results During Installation Proportional Hazards Regressions Odds Ratio Univariate 0.41 p<.001 Multivariate Age, BAC, Prior Arrests 0.35 p<.001 Here are the results of the corresponding Cox regressions. The recidivism of the interlocked group is only 35% of that of the control group after adjusting for age, gender, BAC, and priors arrests. Roth Revocation Alternative Annecy

Half of Interlocks were removed in less than 6 months Recall that the median installation time of interlocks was less than 6 months and that many were removed in 90 days. This slide shows recidivism from installation to the end of the study period including time after interlock removal for most interlocked offenders. This slide shows substantially less over all recidivism for the interlocked group. Half of Interlocks were removed in less than 6 months Roth Revocation Alternative Annecy

Cox Regression Results Including After-Removal Period Proportional Hazards Regressions Odds Ratio Univariate 0.61 p<.001 Multivariate Age, BAC, Prior Arrests 0.56 p<.001 The Cox regressions give significant odds ratios of .61 and .56. Roth Revocation Alternative Annecy

Roth Revocation Alternative Annecy 3300/year June 2003-June 2005 Between January 2003 and May 2003, the interlock installation rate was 1000 per year, but after the Ignition Interlock License Act went into effect in June 2003, the rate increased to over 3000 per year. The Roth Revocation Alternative Annecy

Roth Revocation Alternative Annecy In order to get an interlock license in New Mexico, an offender has to have proof of insurance and an installed interlock. In the last two years over 5000 licenses have been granted and the rate this year so far is over 3000 per year. Roth Revocation Alternative Annecy

Roth Revocation Alternative Annecy Conclusions Interlocks reduce recidivism by 65% during installation and by 44% overall. An Interlock License Alternative to Hard Revocation triples installation rates. In conclusion, studies in New Mexico show that interlocked offenders have many fewer DWI arrests both while interlocks are installed and over the entire study periods. And the Interlock License Alternative to license revocation triples the interlock installation rates. Roth Revocation Alternative Annecy