Foreign nationals who overstay a visa can become legal permanent residents based on marriage to a U.S. citizen as they were inspected and admitted by an immigration officer. However, because of the legal definition of the term “enter," foreign nationals who are granted parole are not considered to have entered the country. They are considered arriving aliens and have fewer rights than those who entered.
Immigration grants parole for various reasons, including for humanitarian motives or to obtain the testimony of material witnesses. When the parole is given for a specific period, such as 90 days, or under specific terms it is known as conditional parole.
Arriving aliens may become legal permanent residents while in the U.S. based on marriage to a citizen. However, the process is different than for foreign nationals who made a legal entry.
The regulations specifically state that foreign nationals granted conditional parole after 1986 cannot avail themselves of the privilege of adjustment of status. This only begins to tell the story, though because another regulation states that foreign nationals granted parole CAN adjust status.
In order to resolve the conflict, Immigration decided on a compromise. Only the Citizenship and Immigration Service decides whether arriving aliens can become legal permanent residents. Because those granted conditional parole are considered arriving aliens, Immigration can grant their adjustment of status.