Art. 2.124. PEACE OFFICERS FROM ADJOINING STATES    

(1) during a time in which:

(A) the peace officer from the adjoining state has physical custody of an inmate or criminal defendant and is transporting the inmate or defendant from a county in the adjoining state that is on the border between the two states to a hospital or other medical facility in a county in this state that is on the border between the two states; or

(B) the peace officer has physical custody of the inmate or defendant and is returning the inmate or defendant from the hospital or facility to the county in the adjoining state; and

(2) to the extent necessary to:

(A) maintain physical custody of the inmate or defendant while transporting the inmate or defendant; or

(B) regain physical custody of the inmate or defendant if the inmate or defendant escapes while being transported.

(b) A commissioned peace officer of a state of the United States of America adjoining this state, while the officer is in this state, has under this subsection the same powers, duties, and immunities as a peace officer of this state who is acting in the discharge of an official duty, but only in a municipality some part of the municipal limits of which are within one mile of the boundary between this state and the adjoining state and only at a time the peace officer is regularly assigned to duty in a county, parish, or municipality that adjoins this state. A peace officer described by this subsection may also as part of the officer's powers in this state enforce the ordinances of a Texas municipality described by this subsection but only after the governing body of the municipality authorizes that enforcement by majority vote at an open meeting.