Texas Health and Safety Code - HEALTH & SAFETY § 433.084. Evidence and Testimony

(a) For the purposes of this chapter, the department at all reasonable times shall be given access to documentary evidence of a person being investigated or proceeded against to examine or copy the evidence. The department by subpoena may require the attendance and testimony of a witness and the production of documentary evidence relating to a matter under investigation, at a designated place of hearing in a county in which the witness resides, is employed, or has a place of business.

(b) The commissioner or the commissioner's designee may sign subpoenas, administer oaths and affirmations, examine witnesses, and receive evidence. On disobedience of a subpoena, the department may request the district court to require attendance and testimony of a witness and the production of documentary evidence, and the district court having jurisdiction over the inquiry may order the compliance. Failure to obey the court's order is punishable as contempt.