"Maythe and T.J. married in San Diego a dozen years ago. But Maythe is barred from the US."

The Barbours are just one of thousands of families stuck apart like this because of a little-known rule included in an immigration reform package passed by Congress in 1996. The rule was designed to discourage undocumented immigrants, like Maythe, from staying in the US, as well as thwart fraudulent marriages by individuals hoping to receive legal residency.