321.323  Moving vehicle backward on highway.
  A person shall not cause a vehicle to be moved in a backward direction on a highway unless and until the vehicle can be backed with reasonable safety, and shall yield the right-of-way to any approaching vehicle on the highway or an intersecting highway which is so close as to constitute an immediate hazard.
[C66, 71, 73, 75, 77, 79, 81, §321.323]
89 Acts, ch 296, §35
For applicable scheduled fine, see §805.8A, subsection 6 
Additional penalties for violations causing serious injury or death, see §321.482A