49 U.S. Code § 13505. Transportation furthering a primary business
(a) In General.—Neither the Secretary nor the Board has jurisdiction under this part over the transportation of property by motor vehicle when—
(b) Corporate Families.—
(1) In general.—
In this section, “corporate family” means a group of corporations consisting of a parent corporation and all subsidiaries in which the parent corporation owns directly or indirectly a 100 percent interest.