(a) An operator passing another vehicle:
(1) shall pass to the left of the other vehicle at a safe distance; and
(2) may not move back to the right side of the roadway until safely clear of the passed vehicle.
(b) An operator being passed by another vehicle:
(1) shall, on audible signal, move or remain to the right in favor of the passing vehicle; and
(2) may not accelerate until completely passed by the passing vehicle.
(c) Subsection (b) does not apply when passing to the right is permitted.
Official text of the Texas Transportation Code as published by the Texas Legislative Council.