Sex Offender. Sex Offender Registration and Community Notification Act. Global Positioning System Device. Practice, Civil, Sex offender. Constitutional Law, Ex post facto law, Sex offender. Due Process of Law, Sex offender. Statute, Retrospective statute, Construction. Words, "Is placed on probation."

INDICTMENTS found and returned in the Superior Court Department on January 16, 1997.

A proceeding for revocation of probation was heard by Robert J. Kane, J.

The Supreme Judicial Court granted an application for direct appellate review.

Theodore F. Riordan (Deborah Bates Riordan with him) for the defendant.

M. Catherine Huddleson, Special Assistant District Attorney, for the Commonwealth.

Present: Marshall, C.J., Ireland, Spina, Cowin, Cordy, Botsford, & Gants, JJ.
BOTSFORD, J.

General Laws c. 265, § 47, inserted by St.2006, c. 308, § 8 (§ 47), requires any person who is "placed on probation" after conviction of a designated sex offense to wear a global positioning system (GPS) tracking device for the duration of his or her probation. [FN1]

In March, 2008, a judge in the Superior Court ruled that this statute applied to the defendant, and entered an order modifying the terms of the defendant's probationary sentence to require that he wear a GPS device during his probation. The defendant appealed, and we granted his application for direct appellate review.

We conclude that G.L. c. 265, § 47, by its terms applies to the defendant, because he was "placed on" postconviction probation following the statute's effective date of December 20, 2006. We further conclude, however, that G.L. c. 265, § 47, is punitive in effect, and under the ex post facto provisions of the United States and Massachusetts Constitutions, may not be applied to persons who are placed on probation for qualifying sex offenses committed before the statute's effective date. [FN2]

Because the defendant committed and was convicted of his qualifying sex offense before § 47 was enacted, the statute may not be applied to him. We therefore vacate the order of the Superior Court judge and remand for further proceedings. [FN3]