Normally, the burden of proof is on the noncitizen to prove admissibility. See, e.g. 22 C.F.R. 40.6.  However, unlike other grounds of inadmissibility, the "reason to believe" ground is based on the immigration or consular official's belief.  Thus, courts have held that here the DHS has the burden to produce reasonable, substantial and probative evidence to establish this ground of inadmissibility.  Alarcon-Serrano v. INS, 220 F.3d 1116 (9th 2000).