(a) A county that has a population of more than 1.3 million and in which a municipality with a population of more than one million is primarily located shall insure its sheriff, constables, and full-time deputies of those officers against liability to third persons arising from the operation or maintenance of:
(1) county-owned or county-leased motor vehicles; and
(2) privately owned motor vehicles to the extent used for the performance of county business or law enforcement duties.
(b) A county may satisfy the requirement of Subsection (a) by requiring that the person to be covered purchase an extended coverage endorsement to an individually owned liability insurance policy and by reimbursing the person for the cost of the extended coverage endorsement. The extended coverage endorsement must be in an amount equal to or greater than that required by Subsection (d) and must extend coverage to include the operation of vehicles in the scope of the person’s employment. The county may require a person insured in this manner to provide proof of coverage.

(c) A county may elect to comply with the requirements of this section by self-insuring in accordance with Section 601.124, Transportation Code.
(d) Liability coverage required under this section must be in amounts equal to or greater than the amounts required by Chapter 601, Transportation Code.
(e) In this section, “motor vehicle” means a vehicle for which motor vehicle insurance is written under Subchapter A, Chapter 5, Insurance Code.