Maryland Code, Transportation § 21-604

(a) A person may not turn a vehicle at an intersection, unless the vehicle is in the position required by § 21-601 of this subtitle.

(b) A person may not turn a vehicle to enter a private road or driveway or otherwise turn a vehicle from a direct course or move it right or left on a roadway or from a shoulder or bikeway onto a roadway, unless the movement can be made with reasonable safety.

(c) A person may not, if any other vehicle might be affected by the movement, turn a vehicle until he gives an appropriate signal in the manner required by this subtitle.

(d) When required, a signal of intention to turn right or left shall be given continuously during at least the last 100 feet traveled by the vehicle before turning; except that a bicyclist may interrupt the turning signal to maintain control of the bicycle.

(e) If there is an opportunity to signal, a person may not stop or suddenly decrease the speed of a vehicle until he gives an appropriate signal in the manner required by this subtitle to the driver of any other vehicle immediately to the rear.

(f) The signals provided for in § 21-605(b) and (c) of this subtitle: