On Monday, Judge Paul Friedman, sitting in US District Court in Washington, DC, dismissed the lawsuit brought against US Department of Interior and the Bureau of Land Management by In Defense of Animals, wildlife ecologist Craig Downer and children's author Terri Farley.
The judge dismissed the case based on the standing of the plaintiffs in the case and the mootness of their argument, given that the muster had already taken place.
The case has been in the public eye over its challenge to the US Government's right to hold horses in long-term holding facilities in the Midwest, away from their western rangelands. The ruling by the judge meant no decision was forthcoming on this question, which the judge had indicated at an earlier hearing appeared to have merit.
"Today's decision did not address the merits of that argument, only the lack of standing by plaintiffs to bring it," said William Spriggs, lead counsel in this case, which is being handled for free by the law firm Buchanan, Ingersoll & Rooney.
"The judge also ruled that the arguments challenging the roundup methods were moot because the roundup had already occurred.
"We remain confident in the merits of our case and look forward to pursuing this legal issue in the near future," Spriggs said.
"The bureau's practice of removing horses from the western range and warehousing them in Midwestern holding facilities is flat out illegal, and the judge's preliminary ruling in this regard was correct."
In a preliminary ruling, the court had agreed that the government's practice of sending wild horses to the Midwest and warehousing them in long-term holding facilities was likely illegal.
The Calico muster of 1922 wild horses earlier this year was one of the largest roundups in recent years.
The bureau removed at least 80-90 per cent of the Calico wild horse population, leaving behind an estimated 600 horses on the 550,000 acre (859 square mile) area in northwest Nevada.
The roundup ended on February 4, 2010, 500 horses short of its target for removal.
To date, 97 of the mustered horses have died during or after the roundup and more than 50 heavily pregnant mares have spontaneously aborted foetuses due to the stress of the roundup and holding.
Wild horses comprise a small fraction of grazing animals on public lands, where they are outnumbered by livestock nearly 50 to 1.
The bureau recently increased cattle-grazing allotments in areas where wild horses are being removed.
Currently, the bureau manages more than 256 million acres of public lands, of which cattle grazing is allowed on 160 million acres. Wild horses are allowed on only 26.6 million acres of this land, which must be shared with cattle.
The bureau plans to remove nearly 12,000 wild horses and burros from public lands by October 2010.
There are currently more than 36,000 wild horses held in government holding facilities, with only 33,000 horses still free on the range.