To be unaware of the facts or the inside story of a situation.

person in the know; someone who has inside information, often regarding a legal case or crime

(idiom) sensible and understanding of others; fair and standing to reason

Legal or ethical requirement to inform a person of the risks and benefits of a procedure before they agree to it

guarantor who has complete knowledge of the situation and takes full responsibility

the right of a party involved to know the facts or true situation within the scope allowed by law