The Department of Homeland Security (DHS) used an incriminating written statement from the petitioner's ex-wife to prove that he had committed marriage fraud.  The DHS did not produce the wife for testimony.  The DHS had sought a subpoena for a prior hearing date for the ex-wife, but there was no evidence that it was served on her, and the DHS did not request a subpoena for the final merits hearing.  The Court found that the DHS did not engage in sufficient efforts to produce the ex-wife.

The full text of Karroumeh v. Lynch can be found here: