Tex. Labor Code § 504.019

(a) In this section:

(1) "First responder" means an individual employed by a political subdivision of this state who is:

(A) a peace officer under Article 2A.001, Code of Criminal Procedure;

(B) a person licensed under Chapter 773, Health and Safety Code, as an emergency care attendant, emergency medical technician, emergency medical technician-intermediate, emergency medical technician-paramedic, or licensed paramedic; or

(C) a firefighter subject to certification by the Texas Commission on Fire Protection under Chapter 419, Government Code, whose principal duties are firefighting and aircraft crash and rescue.

(2) "Post-traumatic stress disorder" means a disorder that meets the diagnostic criteria for post-traumatic stress disorder specified by the American Psychiatric Association in the Diagnostic and Statistical Manual of Mental Disorders, fifth edition, or a later edition adopted by the commissioner of workers' compensation.

(b) Post-traumatic stress disorder suffered by a first responder is a compensable injury under this subtitle only if it is based on a diagnosis that:

(1) the disorder is caused by one or more events occurring in the course and scope of the first responder's employment; and

(2) the preponderance of the evidence indicates that the event or events were a producing cause of the disorder.

(c) For purposes of this subtitle, the date of injury for post-traumatic stress disorder suffered by a first responder is the date on which the first responder first knew or should have known that the disorder may be related to the first responder's employment.