It shall be unlawful for any common carrier by motor vehicle engaged in transportation between points in this state to make, give, or cause any undue or unreasonable preference or advantage to any particular person or locality in any respect whatsoever, or to subject any particular person or locality to any unjust discrimination or any undue or unreasonable prejudice or disadvantage in any respect whatsoever.
RSA 266-A:15
1941, 224:15. RL 304:15.