Iowa drivers...If you've got a license plate frame on your vehicle, you may be breaking the law.  If the frame covers up the county name--even a little, you can be pulled over!  A decision just handed down today by the Iowa Supreme Court says that police can now stop a vehicle "anywhere and at any time" without any other sign of criminal activity if the numbers and letters on your plate are obscured.  If police can't fully read the word "SCOTT" in the county portion on the bottom of the plate…they've got all the probable cause they need to pull you over.

The ruling says:
"Iowa Code section 321.37(3) makes it unlawful “for the owner of a vehicle to place any frame around or over the registration plate which does not permit full view of all numerals and letters printed on the registration plate.”  License plates are primarily functional items, and it is not unreasonable to prohibit decorative items or accessories that affect that functionality even to a small degree.” Although the county name is unnecessary to conduct a license plate check, it can be useful to help law enforcement track down a vehicle driven by someone who has been observed breaking the law. "

In other words, anything that you put around or on your plate that blocks ANY number or letter is a violation and you're asking to get pulled over.  I guess this isn't just limited to license plate frames.  Ever see those people who plaster registration stickers all over the plate?  If one of those stickers covers any part of any letter, you're breaking the law too.

Here's the full ruling:
http://www.iowacourtsonline.org/About_the_Courts/Supreme_Court/Supreme_Court_Opinions/Recent_Opinions/20140502/12-0139.pdf

I found a post on this website where they make the statement that "(in Iowa) At least they still allow Rob's license plate frame…"  Well, not anymore they don't!
(from yucca man.com)

Now illegal:

via Yuccaman.com