49 CFR §1572.107

1. (a)TSA may determine that an applicant poses a security threat based on a search of the following databases:
   1. (1)Interpol and other international databases, as appropriate.
   2. (2)Terrorist watchlists and related databases.
   3. (3)Any other databases relevant to determining whether an applicant poses, or is suspected of posing, a security threat, or that confirm an applicant's identity.
2. (b)TSA may also determine that an applicant poses a security threat, if the search conducted under this part reveals extensive foreign or domestic criminal convictions, a conviction for a serious crime not listed in 49 CFR 1572.103, or a period of foreign or domestic imprisonment that exceeds 365 consecutive days.