32 C.F.R. § 634.23
Personnel registering POVs on DOD installations must consent to the impoundment policy. POV registration forms will contain or have appended to them a certificate with the following statement: "I am aware that (insert number and title of separate Service or DLA directive) and the installation traffic code provide for the removal and temporary impoundment of privately owned motor vehicles that are either parked illegally, or for unreasonable periods, interfering with military operations, creating a safety hazard, disabled by accident, left unattended in a restricted or control area, or abandoned. I agree to reimburse the United States for the cost of towing and storage should my motor vehicle(s), because of such circumstances, be removed and impounded."
32 C.F.R. § 634.23