Tex. Local Government Code § 375.098: DISTRICT ACT OR PROCEEDING PRESUMED VALID.

(a) A governmental act or proceeding of a district is conclusively presumed, as of the date it occurred, valid and to have occurred in accordance with all applicable statutes and rules if:

(1) the third anniversary of the effective date of the act or proceeding has expired; and

(2) a lawsuit to annul or invalidate the act or proceeding has not been filed on or before that third anniversary.

(b) This section does not apply to:

(1) an act or proceeding that was void at the time it occurred;

(2) an act or proceeding that, under a statute of this state or the United States, was a misdemeanor or felony at the time the act or proceeding occurred;

(3) a rule that, at the time it was passed, was preempted by a statute of this state or the United States, including Section 1.06 or 109.57, Alcoholic Beverage Code; or

(4) a matter that on the effective date of this section:

(A) is involved in litigation if the litigation ultimately results in the matter being held invalid by a final judgment of a court; or

(B) has been held invalid by a final judgment of a court.

Added by Acts 2011, 82nd Leg., R.S., Ch. 912 (S.B. 1234), Sec. 10, eff. September 1, 2011.