California Penal Code
A county probation department may utilize a continuous electronic monitoring device pursuant to this section that has all of the following attributes:
(a) A device designed to be worn by a human being.
(b) A device that emits a signal as a person is moving or is stationary. The signal shall be capable of being received and tracked across large urban or rural areas, statewide, and being received from within structures, vehicles, and other objects to the degree technically feasible in light of the associated costs, design, and other considerations as are determined relevant by the county probation department.
(c) A device that functions 24 hours a day.
(d) A device that is resistant or impervious to unintentional or willful damage.