http://www.straightdope.com/columns...ting-flyers-under-my-door-or-on-my-windshield
What about your car? Same deal, pretty much. Nobody has a legal right to touch your car. (Well, some people do: emergency workers, city tow truck operators, etc.) Just like with your house, most jurisdictions recognize a right to use reasonable force to protect personal property. But don't overdo it. Reasonable force would likely be minimal in this context the threat to your property is somewhere between minor and nonexistent, and your personal safety isn't in jeopardy. And of course this assumes you catch the person in the act of putting the flyer on the car.
Beyond that, legal remedies are scarce. Courts call interference with personal property that doesn't deprive the owner of possession "trespass to chattel" or "trespass to personalty." But in this kind of case, you usually can't get nominal damages you've got to show that the trespasser actually damaged the property. While you might be able to get an injunction, it probably wouldn't be worth much. So unless you're prepared to stake out your own car until the flyer guy comes back, then argue in court that shreds of copier paper have reduced the effectiveness of your wiper blades, it's possible that he may never be brought to justice.
Some jurisdictions actually have criminal provisions to deal with people who leave flyers on cars. For example, in 2001 the Ohio Court of Appeals affirmed a conviction under a ordinance in the city of Mount Vernon that barred the placement of printed materials (including handbills) on any privately owned "structure or thing" (including vehicles) without the owner's permission; the defendant had printed up flyers about his exwife and stuck them on windshields in various parking lots. The Ohio court didn't address any Constitutional challenges to the ordinance, though; if the other cases that did are any indication, the law probably wouldn't hold up.
