Deadlock seal

A deadlock seal is a form of lock, or a device added to a lock. A deadlock seal is more secure than most locks, so secure that even a sonic screwdriver cannot open one. It appears to be the only lock the Doctor cannot open.

• The Krillitanes invading Earth in 2007 used deadlock seals, as did the Bane in 2008 and the Humans responsible for the manufacture of cargo ships for that reason. (DW: School Reunion)
• Adipose Industries Headquarters could be deadlocked, this included doors and windows. The deadlocks there can be activated remotely, on command. The computer built into the Adipose Industries Headquarters building (The Inducer) was said to be triple deadlocked, however, the Doctor was able to open these locks after acquiring the sonic device of the owner of the building, Miss Foster. (DW: Partners in Crime)
• Furthermore, it appears that the ATMOS units built by Luke Rattigan are deadlocked into the cars they are fitted into. (DW: The Sontaran Stratagem)
• It is possible that one way to create deadlock seals is with a sonic device, as the Doctor has "locked" several things during his travels, particularly the controls of his TARDIS, which then even the Master could not unlock. (DW:42, Utopia, The Sound of Drums, Last of the Time Lords) (SJA: Invasion of the Bane)