31 Pa. Stat. § 700j-305
In order to enable the board to carry out the provisions of this act, it shall have the power to issue subpoenas requiring the attendance and testimony of, or the production of pertinent books and papers by, milk dealers or handlers or their employes, producers or their employes, persons having business dealings with milk dealers or handlers or producers, or other persons whom the board believes to have information, books or papers of importance to it in carrying out the purposes and intent of this act. Each member of the board and such officers, employes or others employed in the work of the board designated by the chairman of the board also shall have the power to administer oaths and affirmations, to question witnesses thereunder, and to examine such books and papers. The board may issue commissions, letters rogatory, or other appropriate processes outside the Commonwealth.
31 P.S. § 700j-305