By John R. Ellement GLOBE STAFF  MARCH 26, 2019

Convicted sex offenders retain a constitutional right to privacy, and those rights are being violated by a state law mandating that everyone convicted of some sex crimes wear a GPS monitoring bracelet as part of their sentence, the state’s highest court ruled Tuesday.

In a 7-0 ruling, the Supreme Judicial Court decided that privacy protections found in both the state and federal constitutions apply to sex offenders, who are entitled to a case-by-case review of whether GPS monitoring is needed to protect society.

“The government does not have an ‘unlimited’ ability to infringe upon a probationer’s still-existing, albeit diminished, expectations of privacy,’’ Justice Frank M. Gazianowrote for the court. “GPS monitoring is not a minimally invasive search.”

The court said judges must now make an “individualized” determination that GPS monitoring is necessary in order to protect the public, especially children, from the offender, and will also decide whether GPS monitoring will help with rehabilitation of the defendant.Get Metro Headlines in your inbox:The 10 top local news stories from metro Boston and around New England delivered daily.Sign Up

“Mandatory, blanket imposition of GPS monitoring on probationers, absent individualized determinations of reasonableness, is unconstitutional under the Massachusetts Declaration of Rights,’’ Gaziano wrote.

The decision was issued in the case of Ervin Feliz, who pleaded guilty in Suffolk Superior Court to possession and distribution of child pornography and was ordered to spend five years on probation during which he would wear a GPS device and be monitored by the state probation department.

Feliz, who was also ordered to wear a GPS device while awaiting trial, argued the mandate should not apply to him in part because the probation department’s monitoring system excessively triggers alerts even when he was in compliance.

His attorney, David R. Rangaviz, also argued that his client is not a public safety risk and was classified as a Level 1 sex offender by the Sex Offender Registry Board, which meant he was considered least likely to reoffend.

In its ruling, the SJC said that Feliz will no longer have to wear a GPS device because prosecutors have not shown he is a danger to children, because his conviction was a “noncontact sex offense,” and because an expert did not consider him a threat to public safety.

“The reproduction and dissemination of child pornography itself harms the children who are depicted and revictimized with each viewing,’’ Gaziano wrote. But “the Commonwealth’s particularized reasons for imposing GPS monitoring on this defendant do not outweigh the privacy intrusion occasioned by the requirement of GPS monitoring.”

Rangaviz on Tuesday applauded the decision as one that reinforces public safety, not diminishes it. Studies have shown low-risk offenders wearing GPS devices can lose housing and jobs due to false alarms from GPS devices, eliminating stabilizing factors needed for successful rehabilitation.

And judges can still order the use of GPS, he noted.

“If you treat sex offenders [as] one category of people and you don’t treat them as individual human beings, the system isn’t going to work well from a public safety perspective,’’ he said. “From a public safety perspective, this is the best result.”

Gaziano wrote that GPS monitoring is an invasive government act that continues for days, weeks, or months, and is not a one-time intrusion like the law requiring defendants to provide a DNA sample collected by briefly swabbing a person’s mouth.

“GPS monitoring gathers vastly more information than otherwise would be collected in accordance with a defendant’s other conditions of probation” including where one is physically located, how fast they are traveling, and whether one is walking, running, or driving, and stores all of the data for potential later use by government agencies.

“In these circumstances, the government interests do not outweigh the privacy infringement occasioned by GPS monitoring,’’ Gaziano wrote.

The court noted, however, that a judge can readily find that another sex offender, especially those classified as Level 2 and Level 3 and therefore more likely to reoffend, should be monitored by a GPS bracelet.

According to the SJC, more than 3,900 people are currently being monitored through the GPS program operated by the probation department. The ruling potentially affects 879 convicted sex offenders, according to the department.

Rangaviz said he hoped to have the GPS device removed from his client as soon as possible.John R. Ellement can be reached at ellement@globe.com. Follow him on Twitter @JREbosglobe.