that doesn't make a lot of sense to me. That doesn't mean it's accurate, but it doesn't make sense, and currently I don't believe it. I'd have to see the wording of the law.
... which I just did for Virginia
Operation of any motor vehicle in excess of a maximum speed limit established ... shall be unlawful and constitute a traffic infraction punishable by a fine
-http://leg1.state.va.us/cgi-bin/legp504.exe?000+cod+46.2-878.2 (a page on Virginia's official government page, showing the "code of Virginia" -- the body of laws)
I don't see how that can possibly be construed to mean that speeding is finable but not "illegal."
Utah's body of laws is a heckuva a lot more messed up and hideous. Far as I can tell, what you say may possibly be accurate for Utah, since I can find a section specifying the authority to establish a speed limit, and I can find a section on penalties for exceeding the speed limit, but I can't find any word that states "unlawful" or "illegal." However, that sounds more like mincing words.
and on that note, I can't find those words used in conjunction with murder either. There are some types of homocide which are specfically designated 2nd degree felonies, but the crime of "murder," from my cursory search is not specifically labeled "illegal" or an inarguable term giving it equivelant status. would your friend argue this is not illegal either -- just punishable by a jail term? that doesn't make sense.
Seems to me, if it's prohibited or described as "punishable" in the code of the state, it's illegal. Anything else is pulling a Clintonesque "depends on what the meaning of the word 'is' is" sort of semantic bashing that is ultimately meaningless.