For centuries the political makeup of Tigan has been in flux due to the society altering effects of Tigan politicians rewriting Tigan history via the Tigan interface, a device every member of the society is implanted with which informs them of the latest updates to the Tigan central computer, the store of all Tigan history. In the year 2364 Chancellor Lomac was knocked from power via this mingling, how many other chancellors might have been replaced by these means is unclear.
Before being replaced, Chancellor Lomac chose to break with the Tigans' traditional isolationist stand and open up communications with the Federation. His successor Kadec did not support this move and fired on the USS Enterprise-D above and attacked ship's personnel on the planet.
- The extent of Kadec's conspiring is unclear, she may herself have had her memory rewritten, but she was, upon becoming chancellor at the very least, aware of the practice, whether she was responsible for the move to replace Lomac is unknown.
Kadec was herself taken from power when Edic, her co-conspirator saw the error of his ways and arrested her for crimes against state. Edic headed up the next Tigan government, presumably under the traditional chancellor title. (TNG - The Space Between comic: "History Lesson")