3.38 OBJECT BALL FROZEN TO CUSHION OR CUE BALL
This rule applies to any shot where the cue ball's first contact with a ball is with one that is frozen to a cushion or to the cue ball itself. After the cue ball makes contact with the frozen object ball, the shot must result in either:
(a) A ball being pocketed, or;
(b) The cue ball contacting a cushion, or;
(c) The frozen ball being caused to contact a cushion attached to a
separate rail, or;
(d) Another object ball being caused to contact a cushion with which it was
not already in contact. Failure to satisfy one of those four requirements is a foul. (Note: 14.1 Continuous and other games specify additional requirements and applications of this rule; see specific game rules.) A ball which is touching a cushion at the start of a shot and then is forced into a cushion attached to the same rail is not considered to have been driven to that cushion unless it leaves the cushion, contacts another ball, and then contacts the cushion again. An object ball is not considered
frozen to a cushion unless it is examined and announced as such by either
the referee or one of the players prior to that object ball being involved
in a shot.