As always the Texas Code leaves a lot to Officer "Interpretation".
(a) A motor vehicle lamp or illuminating device, other than a headlamp, spotlamp, auxiliary lamp, turn signal lamp, or emergency vehicle or school bus warning lamp, that projects a beam with an intensity brighter than 300 candlepower shall be directed so that no part of the high-intensity portion of the beam strikes the roadway at a distance of more than 75 feet from the vehicle.
(b) Except as expressly authorized by law, a person may not operate or move equipment or a vehicle, other than a police vehicle, with a lamp or device that displays a red light visible from directly in front of the center of the equipment or vehicle.
(c) A person may not operate a motor vehicle equipped with a red, white, or blue beacon, flashing, or alternating light unless the equipment is:
(1) used as specifically authorized by this chapter; or
(2) a running lamp, headlamp, taillamp, backup lamp, or turn signal lamp that is used as authorized by law.
(d) A vehicle may be equipped with alternately flashing lighting equipment described by Section 547.701 or 547.702 only if the vehicle is:
(1) a school bus;
(2) an authorized emergency vehicle;
(3) a church bus that has the words "church bus" printed on the front and rear of the bus so as to be clearly discernable to other vehicle operators;
(4) a tow truck while under the direction of a law enforcement officer at the scene of an accident or while hooking up to a disabled vehicle on a roadway; or
(5) a tow truck with a mounted light bar which has turn signals and stop lamps in addition to those required by Sections 547.322, 547.323, and 547.324, Transportation Code.
- See more at:
http://codes.lp.findlaw.com/txstatutes/TN/7/C/547/D/547.305#sthash.okkmsvEv.dpuf