State appellate courts use mandamus to correct trial judges who fail to rule, exceed their authority, or refuse to follow settled law.
Just as federal courts of appeals can use mandamus to direct district judges, state appellate courts commonly use mandamus (or its state-specific equivalent) to address trial court conduct that cannot wait for an ordinary appeal.
Compelling a ruling on a pending matter
One of the most common uses of judicial mandamus at the state level is compelling a trial judge who has failed to rule on a pending motion for an unreasonable period — sometimes months or longer — to issue a decision.
Correcting a clear abuse of discretion
Beyond simple inaction, mandamus can address situations where a trial judge has issued an order that clearly exceeds the judge's legal authority, such as ordering discovery of information that is unambiguously privileged, or refusing to recuse despite a clear statutory conflict of interest.
The "no adequate remedy by appeal" requirement in this context
Because an ordinary appeal generally must wait until final judgment, state appellate courts examine whether waiting for that appeal would cause irreparable harm that a later reversal could not fix — a discovery order compelling disclosure of privileged material, for example, cannot be meaningfully undone after the fact.
Filing procedure against a judge
These petitions typically name the judge in an official capacity as the nominal respondent, while the actual opposing party in the underlying case is served as the real party in interest and given an opportunity to respond, since that party's interests are most directly affected by the outcome.
Why courts guard this power carefully
Appellate courts are conscious that liberal use of mandamus against trial judges would effectively allow parties to seek piecemeal appellate review of every unfavorable ruling, undermining the efficiency of the ordinary litigation process. As a result, judicial mandamus remains reserved for genuinely extraordinary circumstances.