Blood control

Blood control was a method of controlling beings via their blood type.

The Sycorax once used it against one-third the population of 2008 Earth. They captured the Earth probe Guinevere One, on which was housed a sample of A-positive Human blood. Then, they inserted the sample into a control matrix, which could then send out signals that had to be obeyed by all those with that blood type. In this way, they were able to make all the people on Earth with A-positive blood stand on top of roofs, apparently ready to jump to their deaths.

On this occasion, the Doctor called blood control a "cheap bit of voodoo", and likened it to hypnosis. Blood control, he said, could not overcome the basic Human survival instinct. Thus, although Earth's A-positive population might have appeared to have been in danger of jumping off roofs, in truth blood control was not strong enough to have actually made them jump.

The Doctor further mentioned that he hadn't "seen blood control for years". This might have indicated that comparatively few races had sufficient technology for blood control. However, it could have meant that it was a long-abandoned technology, or simply that his travels had not brought him into contact with it for a while. (DW: The Christmas Invasion)

Known People Affected

 * Alan
 * The British royal family
 * Sally Jacobs
 * Jason