Level Seven Enforcement Field

A Level Seven Enforcement Field was a form of zonal enforcement field. When a Judoon platoon in search of a fugitive descended upon Gloucester, they put one around the city. Jack Harkness attempted to make contact with the Thirteenth Doctor from a stolen spaceship, but failed to get accurate traces of her due to the Level Seven Enforcement Field, which "interfered with everything". (TV: Fugitive of the Judoon)