One of the statutory requirements for NACARA cancellation of removal is that a person not have been apprehended at the time of entry on after December 19, 1990. An entry requires (1) a crossing into the territorial limits of the United States; (2) inspection and admission by an immigration officer or actual and intentional evasion of inspection; and (3) freedom from official restraint. There are at least two ways in which the government might restrain an individual: (1) it could stop the individual physically at the border or (2) it could monitor the individual as he crosses the border by conducting surveillance of him. However, when the government is alleging the latter situation, the burden is on the government to produce evidence of such surveillance.
The full text of Lopez v. Sessions can be found here: