; and (ii) upon intervening— (I) be heard on all matters arising in the civil action; and (II) file petitions for appeal of a decision in the civil action. (3) Investigatory powers Nothing in this subsection may be construed to prevent the attorney general of a State from exercising the powers conferred on the attorney general by the laws of the State to conduct investigations, to administer oaths or affirmations, or to compel the attendance of witnesses or the production of documentary or other evidence. (4) Limitation on State action while federal action is pending If the Commission has instituted a civil action for a violation of this section, no State attorney general may bring an action under this subsection during the pendency of that action against any defendant named in the complaint of the Commission for any violation of this section alleged in the complaint. (5) Relationship with State-law claims If the attorney general of a State has authority to bring an action under State law directed at acts or practices that also violate this section, the attorney general may assert a claim under State law and a claim under this section in the same civil action. (6) Venue; Service of process (A) Venue Any action brought under paragraph (1) may be brought in— (i) the district court of the United States that meets applicable requirements relating to venue under section 1391 of title 28, United States Code; or (ii) another court of competent jurisdiction. (B) Service of process In an action brought under paragraph (1), process may be served in any district in which— (i) the defendant is an inhabitant, may be found, or transacts business