Many of the perpetrators of recent terrorist attacks in France had criminal records and became radicalized in prison by learning terrorist skills. Since they have not committed new crimes, they cannot be re-incarcerated despite the likelihood they will seek new targets. To address this, the document proposes having previously convicted terrorists and those who traveled to Syria/Iraq wear GPS-enabled electronic ankle monitors to track their locations. Additional measures like prohibiting meetings between offenders and only allowing police-monitored cell phones could help prevent radicalized individuals from coordinating further attacks without excessively restricting civil liberties.