Tex. Labor Code § 417.004: EMPLOYER LIABILITY TO THIRD PARTY.

In an action for damages brought by an injured employee, a legal beneficiary, or an insurance carrier against a third party liable to pay damages for the injury or death under this chapter that results in a judgment against the third party or a settlement by the third party, the employer is not liable to the third party for reimbursement or damages based on the judgment or settlement unless the employer executed, before the injury or death occurred, a written agreement with the third party to assume the liability.

Acts 1993, 73rd Leg., ch. 269, Sec. 1, eff. Sept. 1, 1993.