Matter of YL, 24 I. & N. Dec. 151 (BIA 2007) (to determine whether an application for asylum is frivolous, the Immigration Judge must address the question of frivolousness separately and make specific findings that the applicant deliberately fabricated material elements of the asylum claim; the applicant must be given sufficient opportunity to account for any discrepancies or implausible aspects of the claim, and Immigration Judge must provide cogent and convincing reasons for determining that a preponderance of the evidence supports a frivolousness finding, taking into account any explanations by the applicant for discrepancies or implausible aspects of the claim).
http://www.usdoj.gov/eoir/vll/intdec/vol24/3563.pdf