29 C.F.R. § 101.37

Whenever it is deemed advisable to seek temporary injunctive relief under section 10(j) or whenever it is determined that a complaint should issue alleging violation of section 8(b)(4) (A), (B), or (C), or section 8(e), or section 8(b)(7), or whenever it is appropriate to seek temporary injunctive relief for a violation of section 8(b)(4)(D), the officer or regional attorney to whom the matter has been referred will make application for appropriate temporary relief or restraining order in the district court of the United States within which the unfair labor practice is alleged to have occurred or within which the party sought to be enjoined resides or transacts business, except that such officer or regional attorney will not apply for injunctive relief under section 10(l) with respect to an alleged violation of section 8(b)(7) if a charge under section 8(a)(2) has been filed and, after preliminary investigation, there is reasonable cause to believe that such charge is true and a complaint should issue.