By vote of 0 to 9, the supreme court awarded the XYX agency broad discretionary powers enabling of it to withhold from the publice the identities of its source .
Is "it" ambiguously refers to supreme court or XYX agency ???
No. The pronoun would be okay there. Notice that if the Supreme Court wanted to grant itself powers, we would use that pronoun: "itself." We may occasionally see cases like this on the GMAT, where a pronoun can be considered unambiguous because if it were meant to refer back to the subject it would be in the reflexive (-self/-selves) form.