A Covert Authorities Bureau (CAB) is a specialized unit in UK law enforcement/intelligence that centrally manages and ensures legal compliance for all covert operations (like surveillance, informants), handling the administrative paperwork, quality-assuring applications, maintaining records, and liaising with authorizing officers to uphold strict laws like the Regulation of Investigatory Powers Act (RIPA). Essentially, they act as the central hub for legal and ethical oversight of secret intelligence gathering, ensuring proportionality and legality.