Each house shall be the judge of the qualifications and election of its own members; but contested elections shall be determined in such manner as shall be provided by law.
Tex. Const. art. 3, § 8, under Legislative Department.
Tex. Const. art. 3, § 8
EACH HOUSE JUDGE OF QUALIFICATIONS AND ELECTION OF ITS MEMBERS; ELECTION CONTESTS
Each house shall be the judge of the qualifications and election of its own members; but contested elections shall be determined in such manner as shall be provided by law.