The trail in question is FS Trail 115/136, which is part of a series of trails that once encircled the Crazy Mountains, north of Big Timber. On November 23, 2016, Gregoire parked at the Big Timber Canyon Picnic Area on Big Timber Canyon Road and set off on foot for a roughly 500 acre parcel of USFS land to the north, using his GPS app to make sure he stayed on the FS 115/136 trail. When he returned from his elk hunt, he found an officer from the Sweetgrass County Sheriff's Department waiting for him with a $585 fine for criminal trespass. Gregoire has been charged with illegally crossing the Hailstone Ranch, which belongs to the Langhus family of Big Timber. His case goes to an omnibus hearing on February 16, when the judge will review evidence and testimony collected at the time of the arrest. See the Billings Gazette article by Brett French about the case here.
Gregoire has already entered a not guilty plea, and he plans to challenge the trespass charge with evidence of historic usage of the FS 115/136 trail by the public. Such evidence would lend credibility to the argument that there is a "prescriptive easement" on the trail, which is an easement established by historic use that cannot be bought, sold, or granted. For more information on what a prescriptive easement is, look here.
The trail had been in use for a half-century before the Langhus family acquired the adjacent property, and in regular use by USFS crews, as recently as last year, when, as Brett French reports, the Yellowstone district ranger organized a trail clearing crew on the very same trail. At one point there was even a USFS cabin near the same trailhead where Gregoire parked and began his hike. The trail is clearly marked and labeled on USFS topo maps that predate Langhus ownership of the Hailstone Ranch. For their part, the Langhus family is trying to say that there was never an FS trail on the site, and therefore there is no prescriptive easement. The burden of proof, they say, is on the USFS.
Regardless of the outcome of Gregoire's trespass case, which will go before a Sweetgrass County court, the status of the prescriptive easement on FS 115/136 will remain in limbo. In order for the status of the trail to be legally determined, a civil suit will have to be brought against the landowners alleging that there is a prescriptive easement and showing evidence of historic usage by the public that predates private ownership.
Gregoire is seeking help from anyone who has used the trail recently or whose family members used the trail without conflict in the past. Gregoire's supporters have also launched a website to help him crowd-fund his anticipated legal expenses. The page has photos of historic USFS structures at the trailhead and a topo map from 1937 showing the FS 115/136 trail as it existed at the time.