Question:
Answer:
Apart from the Pope, the Bishop of Rome, no priest or bishop has the power to unilaterally grant an annulment. However, even the Pope is not likely to ordinarily intervene in a marriage case decided by the Roman Rota, which ordinarily adjudicates annulment cases appealed to Rome, or the Supreme Tribunal of the Apostolic Signatura, which is the Catholic equivalent of the U.S. Supreme Court. But the Pope could overrule a decision made by either entity.
On the diocesan level, a parish priest assists his parishioners in filing petitions for annulments with the diocesan marriage tribunal. In turn, the diocesan bishop oversees judicial appointments to the marriage tribunal and has thus has the responsibility to ensure the rights of those who file and oppose such petitions are respected.
For more information on a specific case, contact your diocesan tribunal, and you may consider hiring a canon lawyer if needed.