§ 20‑16.3A. Checking stations and roadblocks.
(a) A law‑enforcement agency may conduct checking stations to determine compliance with the provisions of this Chapter. If the agency is conducting a checking station for the purposes of determining compliance with this Chapter, it must:
(1) Repealed by Session Laws 2006‑253, s. 4, effective December 1, 2006, and applicable to offenses committed on or after that date.
(2) Designate in advance the pattern both for stopping vehicles and for requesting drivers that are stopped to produce drivers license, registration, or insurance information.
(2a)
Operate under a written policy that provides guidelines for the pattern, which need not be in writing. The policy may be either the agency's own policy, or
if the agency does not have a written policy, it may be the policy of another law enforcement agency, and may include contingency provisions for altering either pattern if actual traffic conditions are different from those anticipated, but no individual officer may be given discretion as to which vehicle is stopped or, of the vehicles stopped, which driver is requested to produce drivers license, registration, or insurance information. If officers of a law enforcement agency are operating under another agency's policy, it must be stated in writing.
(3)
Advise the public that an authorized checking station is being operated by having, at a minimum, one law enforcement vehicle with its blue light in operation during the conducting of the checking station.
(a1) A pattern designated by a law enforcement agency pursuant to subsection (a) of this section shall not be based on a particular vehicle type, except that the pattern may designate any type of commercial motor vehicle as defined in G.S. 20‑4.01(3d). The provisions of this subsection shall apply to this Chapter only and are not to be construed to restrict any other type of checkpoint or roadblock which is lawful and meets the requirements of subsection (c) of this section.
(b) An officer who determines there is a reasonable suspicion that an occupant has violated a provision of this Chapter, or any other provision of law, may detain the driver to further investigate in accordance with law. The operator of any vehicle stopped at a checking station established under this subsection may be requested to submit to an alcohol screening test under G.S. 20‑16.3 if during the course of the stop the officer determines the driver had previously consumed alcohol or has an open container of alcoholic beverage in the vehicle. The officer so requesting shall consider the results of any alcohol screening test or the driver's refusal in determining if there is reasonable suspicion to investigate further.
(c) Law enforcement agencies may conduct any type of checking station or roadblock as long as it is established and operated in accordance with the provisions of the United States Constitution and the Constitution of North Carolina.
(d) The placement of checkpoints should be random or statistically indicated, and agencies shall avoid placing checkpoints repeatedly in the same location or proximity. This subsection shall not be grounds for a motion to suppress or a defense to any offense arising out of the operation of a checking station. (1983, c. 435, s. 22; 2006‑253, s. 4; 2011‑216, s. 1.)
http://www.ncga.state.nc.us/EnactedLegislation/Statutes/HTML/BySection/Chapter_20/GS_20-16.3A.html
If the agency doesn't have a written policy they can follow another agencies policy and public notification is having one car with its' blue lights on at the checkpoint.
