dead hand

Short definition from Wiktionary

Noun

1. 1
   A residual undesirable influence from the past.
2. 2
   A hand that is dealt but not used during a card game.
3. 3
   A penalty where a player continues to take their turns, but can no longer win or make tile calls for the remainder of the hand.

Proper noun

1. 1
   A weapons system, implemented by the Soviet Union and by the Russian Federation as the successor state thereof, capable of closing a strategic nuclear strike control loop in the absence of normal command and control channels, analogous in concept to a dead man's switch, in anticipation of a decapitation strike.
2. 2
   Any such system, whether the cardinal instance (the Soviet/Russian one) or another.