Counsel for the appellees argue that the experience rating plan is just in that it imposes on each included taxicab owner as far as practicable his fair share of the cost of liability insurance. They assert also that the experience rating plan is wise in that it affords a twofold encouragement to safety on the highways by offering reduced premiums to included taxicab owners who are better than average risks and by exacting increased premiums from included taxicab owners who aré worse than average risks. They insist, moreover, that the differences in the premium charges for liability insurance are based on reliable evidence as to losses, and that in consequence there is no discrimination among the individual taxicab owners covered by the experience rating plan or between such taxicab owners as a group and other taxicab owners.
We are impressed in no small degree by the apparent validity of these arguments. We are nevertheless constrained to hold that the North Carolina Rate Administrative Office and the Commissioner of Insurance exceeded the powers conferred upon them by Article 25 of Chapter 58 of Yolume 2B of the General Statutes in promulgating and approving the experience rating plan which imposes a premium on each taxicab owned by the petitioner for bodily injury insurance satisfying the requirements of the ordinance of the City of Asheville for the annual period beginning 1 March, 1951, 52 per cent higher than that charged on each taxicab operated by the competitors of the petitioner, whose premiums are measured by the basic or manual rates.
These statutory provisions fall within the purview of the familiar and sound rule of statutory construction embodied in the terse maxim expres-sio unius est exclusio alterius, meaning the expression of one thing is the exclusion of another. When the Legislature granted authority to the North Carolina Automobile Rate Administrative Office and the Commissioner of Insurance “to encourage safety on the highway ... by offering reduced premium rates under a uniform system of experience rating,” it *377impliedly prohibited them from doing that thing in any other way. Howell v. Indemnity Co., ante, 227, 74 S.E. 2d 610; In re Sale of Land of Sharpe, 230 N.C. 412, 53 S.E. 2d 302; Old Fort v. Harmon, 219 N.C. 241, 13 S.E. 2d 423; Botany Worsted Mills v. United States, 278 U.S. 282, 49 S. Ct. 129, 73 L. Ed. 379; Raleigh & G. R. Co. v. Reid, 13 Wall. 269, 20 L. Ed. 570; Stephens v. Smith, 10 Wall. 321, 19 L. Ed. 933; 50 Am. Jur., Statutes, section 244; 59 C.J., Statutes, section 582. This being true, the North Carolina Automobile Rate Administrative Office and the Commissioner of Insurance passed beyond their statutory authority when they sanctioned an experience rating plan which undertakes to encourage safety on the highways by imposing increased premium rates.
For this reason, the premium rates challenged by the petitioner are legally excessive, and the judgment holding that he is not entitled to appropriate relief against them is
Reversed.