Nevada Revised Statutes:

NRS 569.431 “Legal fence” defined. As used in NRS 569.431 to 569.471, inclusive, “legal fence” means a fence with not less than four horizontal barriers, consisting of wires, boards, poles or other fence material in common use in the neighborhood, with posts set not more than 20 feet apart. The lower barrier must be not more than 12 inches from the ground and the space between any two barriers must be not more than 12 inches and the height of top barrier must be at least 48 inches above the ground. Every post must be so set as to withstand a horizontal strain of 250 pounds at a point 4 feet from the ground, and each barrier must be capable of withstanding a horizontal strain of 250 pounds at any point midway between the posts.

(Added to NRS by 1991, 1147)

The real argument about fencing at all comes from newcomers to the state, often those city slickers who buy up homes on the edge of towns and then bellyache about cattle coming onto their land, and why should they have to put up any fence at all. Nevada is an "open range" state, where if you want cattle/sheep kept off your property, you must fence them out. There have been a bunch of people who have complained about this, and Nevada has, by and large, told these people (invariably from Kahl-ee-fornia) that if they don't like it, they can return to that whence they came.

The point where the legal fence issue really comes into play is when you wake up one morning and find cattle that your neighbor has been trying to starve into a profit in your hay barn, munching down some dairy-hot alfalfa. You have two choices at this point:

1. You can keep the cattle in, call the sheriff and have them declared "estray livestock" and charge them boarding fees. Until such time as your neighbor pays the fees, you can impound the cattle, so long as your land was enclosed by a "legal fence." During the time you've impounded the cattle, they'd better not die in your care.

2. In the case where the cattle have been eating hot hay, and you can see them starting to bloat, the best tactic is to get them the heck off your property and kick them out onto the road and let them bloat up and die there.

I've taken choice #2 in the past.

I can tell you for a fact that the NRS definition of "legal fence" is not sheep-tight. It only holds (in or out) cattle. Sheep can (and do) go under the lower wire or between the two lowest wires. You really need a six-wire fence to hold sheep in/out, and with those T-bars 20' apart, you'd better have stays in the middle of the span. Range sheep are mighty persistent buggers. They're not called "range maggots" for no reason.