N.C. Gen. Stat. § 20-379
The Department of Public Safety must periodically audit each motor carrier to determine if the carrier is complying with this Article and, if the motor carrier is subject to regulation by the North Carolina Utilities Commission, with Chapter 62 of the General Statutes. In conducting the audit, the Department of Public Safety may examine a person under oath, compel the production of papers and the attendance of witnesses, and copy a paper for use in the audit. An employee of the Department of Public Safety may enter the premises of a motor carrier during reasonable hours to enforce this Article. When on the premises of a motor carrier, an employee of the Department of Public Safety may set up and use equipment needed to make the tests required by this Article.
N.C. Gen. Stat. § 20-379