Any motor vehicle may be equipped with not to exceed one spot lamp and every lighted spot lamp shall be so aimed and used upon approaching another vehicle that no part of the high-intensity portion of the beam will be directed to the left of the prolongation of the extreme left side of the vehicle nor more than one hundred feet ahead of the vehicle.
Iowa Code § 321.402
Referred to in §321.1, 456A.12, 805.8A(3)(r)
For applicable scheduled fine, see §805.8A, subsection 3