So I happened to come across this official little pamphlet that contains all the rules and regulations and shit for the State of Oregon if you're going to ride on public land. I decided the best way to illustrate how ridiculous this is, is to compile a list of things that are ILLEGAL to do on public lands with a dirt bike.
1) Be Too Young - If you are under the age of 7, it is decreed that you are unworthy of operating a dirt bike, even if it's got a 3-horse lawnmower engine.
2) Go Without a Helmet - This makes sense, really, except the rules say that once you turn 18, you don't need to wear one. Like adults all have craniums of titanium or something.
3) ATV Safety Education Card - Yes, that's right. If you are under the age of 30 in this state, it is required that you have taken a government course either online or in-person, and have an official card with you showing that you've done it. By 2014, everyone must have one of these cards to ride, full-stop.
4) Ride Without a Sticker - The ATV sticker you buy for $10 and goes to fund the people who close down trails and harass riders, is mandatory for all.
5) No Spark Arrestor - It doesn't matter if you are riding in the rainforest (yes, we have a rainforest here) in the dead of winter during a typhoon. Without a government-approved SA, you might as well ride a nuclear bomb as far as the law is concerned.
6) Be Louder than 99dB - Who wares that the acoustics of the area are, or what how the noise will affect the neighbors, if they exist. This law is universal, regardless of the circumstances.
Here's the best one of them all.
7) Riding without Headlight and Tail Light - Yes, that's right. In order to ride on public lands in Oregon, no matter WHAT the visibility is or the time of day, you have to have a tail light and headlight.
The above rules don't apply, however, if you are part of industry, such as forestry or agriculture. In that case, you are likely part of a union that has lobbied the State government to exempt you. Because the Christmas tree industry is WAY more important than recreational riding. Also, if you are on private land, these rules are also exempt. So if you're riding in your back yard, you're good.