Bolsonaro: how an electronic ankle bracelet works and the types of alerts issued

Former president Jair Bolsonaro was arrested after trying to violate the electronic ankle bracelet that was used by him as a precautionary measure as determined by the Federal Supreme Court (STF). Minister Alexandre de Moraes, of the STF, who ordered the preventive detention, stated that there was a risk of escape, given the attempted rape and the “vigil” that was scheduled by senator Flávio Bolsonaro (PL-RJ), near the former president’s condominium.

What are electronic anklets?

Electronic ankle bracelets record the location of people monitored by the Court in real time and send this data to a Monitoring Center.

The equipment, which can weigh a maximum of 300 grams, works as a permanent tracker that collects coordinates, transmits information via encrypted channels and issues alerts when there is a risk of violating the rules imposed on the user.

The ankle bracelet continuously monitors the movement of the person being monitored. When the coordinates indicate leaving an inclusion area (place where the person must remain) or entering an exclusion area (prohibited places), the system generates an automatic notification to the center.

How do alerts work?

The equipment also communicates directly with the user.

If the battery is below 30%, it triggers vibrating, light or audible alerts and repeats the warning at least three times before turning off completely.

In the event of a physical breach, such as an attempt to break the bracelet, an alert is immediately issued to operators.

Among the events that the system notifies are:

Violation or return to the inclusion area

Violation or exit from the exclusion area

Entry or exit from the warning zone

Low battery, recharge or shutdown warnings

Attempt to break the bracelet or damage the device

GPS signal loss

Real-time route

The software used by surveillance teams shows the real-time path of each person being monitored and visually highlights any type of violation. Each alert appears automatically to responsible operators, who can trigger response measures.

In DF, nine servers monitor electronic ankle bracelets.

In addition to monitoring those being investigated and sentenced under house arrest or semi-open conditions, the ankle bracelet is widely used in protective measures against domestic violence, to prevent aggressors from approaching victims. With the accelerated growth in the use of equipment, an increase of 95% between 2016 and 2024, experts point out that the country faces a shortage of personnel to monitor alerts: there are only 181 professionals for more than 120 thousand monitored, the equivalent of one for every 674 people in custody.

Breach Alert

In Bolsonaro’s case, the alert issued was that the equipment had been breached. The former president acknowledged having used a soldering iron to try to open the electronic ankle bracelet. The information is contained in a report from the Federal District Penitentiary Administration Secretariat (SEAPE-DF), prepared after inspection teams were called to verify possible violation of the device.

According to the document, the team initially received communication that the person being monitored had “hit the device on the stairs”. Upon arriving at the scene, the responsible police officer stated that, contrary to initial information, the ankle bracelet “did not show signs of stair shock”. Instead, the report points out that the equipment had “clear and important signs of damage”, including burn marks around the entire circumference, especially in the region where the case closed.

Asked about the instrument used to cause the damage, Bolsonaro replied that he had “used a soldering iron to try to open the equipment”.

According to the document, “the equipment showed clear and important signs of damage”. “There were burn marks around its entire circumference, where the case was fitted/closed,” reported the Integrated Electronic Monitoring Center.

Asked at the time of the performance by Seap employees whether he had used something to burn the ankle bracelet, the former president replied that he had used a “hot iron”. When asked again, he said he used a “soldering iron”.

“Curiosity,” he added.

The loose iron is an electrical tool that, when heating the tip, is capable of melting materials such as tin, but is not suitable for melting plastic, such as the housing of an electronic ankle bracelet, which could dirty or damage the tip of the tool.

The tool is widely used by electronics technicians to repair or assemble electronic circuits, connect wires and in various other metallurgy, electrical and craft applications. The heat generated allows the creation of strong electrical and mechanical connections. The tool is dangerous as it can burn the skin.

Set of tests

Professor at the Rio de Janeiro State Judiciary School (EMERJ) and specialist in criminal law, André Perecmanis explained that the violation in itself would not be grounds for arrest, but all the evidence shows a risk to the guarantee of public order.

The professor also explained that if a violation is found on the part of the monitored person, the Court may decide to remove the person from the regime. This is what happened with Bolsonaro, who was at home and went to prison.

— He was under house arrest, he was under an alternative precautionary measure to avoid preventive detention. When he fails to comply, he is automatically arrested — he explained.

Collor case

This year, former president Fernando Collor also had problems with an electronic ankle bracelet after the equipment was turned off for 36 hours. In December, the defense argued to the STF that there was no intentional shutdown of the equipment and that, therefore, there was no violation of monitoring.

Collor was sentenced to eight years and 10 months in prison for corruption and money laundering in an offshoot of Lava Jato. The equipment was widely used on people convicted or investigated by Lava Jato.