Seven years ago, the Ephrata School District signed an agreement with the late Elam Lauver, whose farm had been the 11th ever preserved in Lancaster County in 1984.
Under the contract, the district would build an access road to a new elementary school through the preserved land. In exchange, Lauver would receive two acres for every acre he gave up.
Lancaster County and the Chesapeake Bay Foundation took the case to court. The Pennsylvania Supreme Court had the final say, ruling against the deal in 2007.
Preservationists said the case represented a landmark.
If the decision had gone the other way, they claimed, perpetual easements everywhere might be endangered.
So, just how solid are land easements that are supposedly designed to last forever?
Leslie Ratley-Beach, defense director of easements for the Land Trust Alliance in Washington, D.C., keeps track of all agricultural and other open space easements in the United States.
She said she knows of no court in the country that has ever "extinguished" a conservation easement of any kind.
Land trusts have lost litigation over "a specific violation that did not threaten the continued effectiveness of the easement," she said, but those have been "relatively minor disputes."
One of the lost cases seems similar to the situation in Lancaster County.
A developer needed an access easement from a neighbor in order to build houses on his land in Clarkstown, N.Y. The neighbor had placed a conservation easement on his farm and so turned down the developer's proposal.
The developer sued and won on the basis that the conservation easement did not prohibit signing over an access easement to the land.
The difference is that Elam Lauver's easement did prohibit signing over an access easement without the approval of the county's preservation board.
Only one legal maneuver can trump solid conservation easements, Ratley-Beach said. That is eminent domain. It has been used to take preserved land.
"Government condemning authorities may seize both the land and the easement following the usual procedures," she said. "This is an issue in all 50 states."
It was an issue in Lancaster County almost a decade ago.
In 2001, the Mount Joy Borough Authority wanted to purchase five acres of Robert and Debbie Bachman's farm in East Donegal Township through eminent domain.
The property is adjacent to the authority's water treatment plant.
The Bachmans reportedly did not oppose the idea, but the state Agricultural Lands Condemnation Approval Board rejected it, saying the authority had not shown a compelling need for the preserved acreage.
If farmland or open space is taken through eminent domain, Ratley-Beach said, conservationists try "to divert the impact to conserved land, minimize it if diversion is not feasible and in the last resort obtain appropriate compensation for any taking."