NOTE: This information is dated 12/09/2014 and may become obsolete in the future
I’ve been researching the legality of strobe brake lights (sometimes referred to as wig-wags). I contacted the Polk County Sheriff Department to ask and they provided the Iowa Code below. I have highlighted the section of interest. It’s ambiguous at best, but it looks like they are legal by the “letter of the law”. I’ve contacted an attorney but have not heard back. Emphasis mine.
Of particular note is the “prohibited except” and the “intent to stop” language.