Temporal Isolator was a piece of kit, which was designed to freeze time. It was considered as outlawed, since it caused radiation leakage and horrific collaterial damage to anything and anyone that gets in its path, leading to civilian casualties. The Thirteenth Doctor called it a "horrible thing".
In 2020, the Judoon threatened to use it to prevent a fugitive from escaping. They were restricted from doing so by the Thirteenth Doctor, who introduced herself as an Imperial Regulator. (TV: Fugitive of the Judoon)