There is no single national statistic, but understanding what drives outcomes can help set realistic expectations.

There is no comprehensive, centralized dataset tracking mandamus outcomes across every state and federal court, and success rates vary considerably depending on the type of claim, the specific court, and how well the petition is prepared.

Delay-based claims tend to fare relatively well when well-documented

Petitions clearly documenting an extended delay well beyond published processing benchmarks, with a straightforward ministerial duty to adjudicate (not to approve), tend to be among the more successful categories of mandamus filings — particularly because many resolve through adjudication rather than a contested ruling.

Petitions challenging discretionary decisions face a much steeper path

Petitions that, in substance, ask a court to override a genuinely discretionary decision face a significantly lower likelihood of success, since courts consistently decline to substitute their judgment for an agency's or official's lawful discretion.

Appellate mandamus against a judge is especially difficult

Petitions seeking mandamus against a trial court judge's ruling face one of the highest bars in all of mandamus practice, given the strong judicial preference for the ordinary appellate process discussed elsewhere on this site.

What meaningfully improves the odds

A clear factual timeline, well-documented exhaustion of administrative remedies, precise identification of a truly ministerial duty, and careful attention to jurisdiction and procedural requirements all measurably improve a petition's chances, regardless of the specific category involved.

Managing expectations honestly

Because mandamus is, by design, an extraordinary remedy reserved for clear cases, petitioners should approach it with realistic expectations rather than viewing it as a routine or guaranteed path to relief.