i just kind of skimmed over this, as it parallels a thread on the same subject on a different board.
As Alvin stated way back in the beginning...the guy was off the trail. No question about it. Coronado National Forest is closed unless posted open (as per the NFS), and the appropriate signs are posted in the area. There are also maps posted at some of the trailheads, staging areas, and major trail junctions, showing the legal trails. When this guy left the road and proceeded across the open desert, he was off the trail. Ther are no legal roads or trails in this area, only places where others have left the trail before this guy. This was not a dry wash, this was not a bypass around anything. The area is moderately vegitated, and the area will not be restored by the next rainfall. In this instance, there was no reasonable person would mistake this area as open for travel given the obviously posted signs reading "vehicle traffic is restricted to trails marked by this [insert trail marker here] symbol"
Now, I understand the critical distinction between "open unless closed" and "closed unless open". I generally support the former...but as I spend more time in the back country, I find more and more wildcat trails, and start to wonder if this policy has major flaws. Without any markers, other than those indicating which trails are closed, how is anyone supposed to know if they are on a legal trail or not? Just because someone else has driven there does not mean I, or anyone else should. If this was the case....all anyone would have to do to open a new trail, is to drive it a couple of times so it becomes a obvious trail. How much more harm can be done by continued use? It won't take long before the back country is nothing but one big trail.
On the other hand, you have Seans (legitimate) arguement about the dry washes.
Really, if everyone played by the rules, the "open unless closed" policy would work great. Problem is, too many people don't play by the rules. So you get wildcat trails which see continued use because of the very policy that we love so much...and these wildcat trails are our biggest enemy (well, one of the top 3 anyway).