Can OFAC designate someone without any prior notice or hearing?

Yes. OFAC operates under an ex parte system, meaning designations are imposed without advance notice or opportunity to respond. The Treasury Department justifies this approach on national security grounds — providing warning would allow targets to move assets before freezing. Designated parties only learn of their status when it appears in the Federal Register or when banks begin blocking transactions. This lack of pre-deprivation process has been challenged constitutionally, but U.S. courts have largely upheld OFAC’s authority. The remedy is post-designation administrative reconsideration, which places the burden on the designated party to disprove the government’s case.