Monitoring bracelet, usually worn on the ankle.
Can be for location, or it may be for alcohol detection. For location, it could be due to domestic violence. For alcohol it could be due to alcohol related vehicle crash, possibly causing injuries or fatalities. The alcohol monitor doesn’t track or detect location.
if it was domestic violence…and if he is from some countries, he would not be allowed by the court to travel. And unlikely to pass through security because it can’t be removed.