[TRD-X]

Originally Posted by pinkmeansdanger

Not sure if you are asking about the legality or not. Generally, that depends on your state and sometimes even your municipality. For instance, here is California's law on Material Obstruction or Reduction of Drivers View. As you can see, such a law is on the books, but judging by all the stickers on cars from California, probably rarely enforced. However, it can be used as a pretext to pull you over and conduct a more through investigation of you and any other laws you may be breaking at the time like DUI, drugs, etc.

The OP was asking because of the rear defroster...