“We have been given the legal advice that we can do this in parallel to the process going on in Washington,” Mr. Howard said. “If we didn’t think we had the authority or ability to do this, we wouldn’t be doing it.”

A senior State Department official, who asked not to be identified because the permit process is continuing, said TransCanada had not sought federal approval to invoke eminent domain. He said the department had no authority on the issue and that it was up to state law and the courts to determine appropriate use of eminent domain laws.

Landowners and their lawyers are pushing local courts to do just that. While it is impossible to say how many cases are working their way through the legal system, in addition to the 56 Texas and South Dakota cases, TransCanada acknowledges it has sent “Dear Owner” letters to dozens of families in Nebraska.

Timothy Sandefur, a lawyer with the Pacific Legal Foundation, a nonprofit advocate for property rights issues, said that if the project is approved, the company will be on firmer ground. As unfair as the laws might seem, he said, the right of way of pipelines and railroads as public goods has been well established, regardless of whether they are foreign-owned. “Property owners almost never win these suits,” he said.

But lawyers for the landowners, particularly in Nebraska, Oklahoma and Texas, argue that TransCanada has not met the requirements to invoke eminent domain under those states’ laws. In South Dakota, however, a judge has already ruled that TransCanada could use eminent domain to secure land for a previous pipeline project.

David A. Domina, a Nebraska lawyer whose firm represents 45 landowners, said there was “no way” that TransCanada has eminent domain powers under Nebraska law, and that the company was “acting in bad faith.”

In East Texas, where residents are used to having cordial dealings with oil companies, landowners said they had never seen a company behave as aggressively as has TransCanada.