Whether a judge can modify a sex offender’s probation to require him to wear a GPS tracking device, absent a probation violation.

The defendant began the probationary portion of his sentence for a set of sex offense convictions in 2009, after serving 15 years in prison and another four years committed as a sexually dangerous person. Although he committed no probation violation, the Commonwealth sought modification of the terms of his probation (apparently concerned that he was not taking his medication, among other issues). The judge granted various modifications, but refused to order the defendant to wear a GPS tracking device.

The Commonwealth appealed to the single justice, and the single justice reserved and reported the case to the full bench.

The judge held that she was barred from imposing GPS monitoring by Commonwealth v. Cory, 454 Mass. 559 (2009), which holds that mandatory GPS monitoring is punitive in effect, and therefore cannot not be applied to offenses committed prior to the statute’s enactment. The judge reasoned that GPS was therefore punitive generally, and she was permitted to impose punitive terms of probation only in original sentencing or in response to a violation, citing Commonwealth v. Chirillo, 53 Mass. App. Ct. 75, 80 (2001).

The Commonwealth argues that Cory stands only for the proposition that mandatory GPS monitoring triggered by a conviction is punitive, and that GPS monitoring triggered by an individual evaluation is not punitive. The defendant argues that Cory stands for the proposition that GPS monitoring is always punitive in effect, and that the mandatory nature of the monitoring at issue in Cory was relevant only to an ex post facto balancing test.