We like to think of our national parks as places that are protected for generations, where outside the visitor center and a few heavily used trails, the vistas, the streams and the wildlife are there now as they have been and ever will be. But some of the West's most iconic parklands—Canyonlands, Bryce, Zion, Death Valley, Glen Canyon, Yosemite—have been under assault in recent years.

Those assaults come from a few renegade counties deciding that the Park Service can't protect rivers, habitat, archaeological sites and wilderness by closing old cattle trails and streambeds to dirt bikes and all-terrain vehicles. The counties claim they own highway rights to these rough tracks under a repealed, 19th Century law known as R.S. 2477.

Earlier this week, a court of appeals ruling turned back one of these assaults in a way that will make sure parks across the West are a little better protected.

In Utah's Grand Staircase-Escalante National Monument, Kane County tried ripping out "road closed" signs, and putting up signs directing vehicles into protected areas of the monument, trumpeting their "rights" under the old law. Kane also passed a law that invited off-road vehicles into closed, protected areas of Glen Canyon National Recreation Area.

Kane County claimed - but didn't prove - historic rights-of-way before it put up those road signs and passed its ordinance. So, four years ago when Earthjustice sued on behalf of people and groups who didn't want these protected lands degraded, the heart of our lawsuit was Kane County's lack of proof. And this is what the 10th Circuit Court of Appeals seized on this week when it ruled against the county's actions.

All judges, including one who dissented, thought the county's actions were illegal. And they weren't just addressing Kane County. The message is clear to those few counties who don't respect America's national heritage:: you can't take the law—or national park lands—into your own hands. That's heartening news for those of us who love these landscapes and know that they should be protected forever.