The TGA allows the BLM to increase or decrease the utilization of a grazing area in response to changing ecological conditions, and specifies that permits are subject to periodic review at least every 10 years, with holders having preferential rights to renew "in the discretion of the Secretary of the Interior." An article written by University of Nevada Cooperative Extension Educators Gary McCuin and Steve Foster, highlights the Nevada Open Range Law of 1893, a state statute under which "owners of ... livestock running at large on the ranges or commons” were exempted from state civil liability for trespass, and the open range was defined as “all unenclosed land outside of cities and towns upon which cattle, sheep or other domestic animals by custom, license, lease or permit are grazed”. However, the federal Taylor Grazing Act has further regulated grazing on federal land since 1934, and violators may be subject to federal civil and criminal liability. The Bureau of Land Management manages about 167 million acres (676,000 km²) of publicly owned rangeland in the United States, with the United States Forest Service managing approximately 95 million acres (380,000 km²) more. Permittees on federal rangelands are required to pay a fee, and the permit cannot exceed ten years but is renewable. Any US citizen or validly licensed business can apply for a BLM grazing permit or lease. To do so, one must either buy or control private property (known as "base property") that has been legally recognized by the Bureau as having preference for the use of public land grazing privileges, or acquire property that has the capability to serve as base property and then apply to the BLM to transfer the preference for grazing privileges from an existing base property to the acquired property (which would become the new "base property"). The grazing rules for the land went through changes over the years, including some updated grazing rules in 1993 in the Gold Butte and Bunkerville land area of Nevada. Among other issues, the 1993 rules were changed to protect the vulnerable desert tortoise. Other rules included limits to the number of cattle allowed in certain areas to protect the lands from the severe overgrazing caused by less regulation in previous years and to help the land recover from recent wildfires. Currently there are no grazing permits on the Bunkerville allotment, and any livestock on that land are there illegally. The Bundy standoff is a 20-year legal dispute between the United States Bureau of Land Management (BLM) and cattle rancher Cliven Bundy in southeastern Nevada over unpaid grazing fees that eventually developed into an armed confrontation between protesters and law enforcement.