You should consult with an experienced immigration attorney and file a Re-Entry Permit application for your alien spouse PRIOR to his initial departure from the U.S. as a current lawful permanent resident to avoid the threat of having abandoned his I-551 "green card". If departure/residence abroad will be in excess of two (2) years, he will need to return prior to the two year period and re-file for another Re-Entry Permit while physically present in the U.S.
Answered on Nov 28th, 2012 at 4:34 PM