Taking implements of husbandry, such as NH3 nurse tanks, across state lines has been a controversial topic over the last few years.  DOT has just recently clarified that implements of husbandry are not commercial motor vehicles (CMV) and therefore not subject to the CMV regulations.  The Federal Motor Carrier Safety Administration's (FMCSA) authority covers persons who operate a commercial motor vehicle in interstate commerce.  Therefore, when an implement of husbandry crosses state lines in interstate commerce it is not subject to CMV regulations since it is not a Commercial Motor Vehicle.