Ermir Spahiu was pulled over by police for his window-mounted GPS unit. For Tina Ross, it was her handicapped placard. And Mark Hubbard was nailed for an air freshener. All three Illinois drivers were stopped for what they thought were innocent items placed near their windshields.

"It really threw me for a loop," said Hubbard, recalling his 2008 encounter with Rolling Meadows police over a 2-inch scented medallion that dangled from his rearview mirror.

An increasing number of drivers are being cited for windshield and window obstructions, which can include anything an officer deems to "materially obstruct" a driver's vision. The only exceptions are government-issued items such as I-PASS boxes and parking stickers.