You can cause someone else to get a $40 ticket.

Originating from Wootton High School, the parent said, students duplicate the license plates by printing plate numbers on glossy photo paper, using fonts from certain websites that "mimic" those on Maryland license plates. They tape the duplicate plate over the existing plate on the back of their car and purposefully speed through a speed camera, the parent said. The victim then receives a citation in the mail days later.
http://www.thesentinel.com/302730670790449.php

This works because unless the ticket is challenged, there is no system in place to verify that the license plate matches the actual vehicle. All you need is a car of the same make & color to fool any human reviewers.

Is this illegal? Yes. But chances of getting caught are very slim -- the cops don't hang around speed camera locations (because... the camera is doing their job!) to see if anyone is driving by with fake paper license plates.

Chip H.