§ 506.Where special proceeding commenced.

Subdivision (a) states the default: unless another rule or the statute authorizing the proceeding says otherwise, a special proceeding may be commenced in any county within the judicial district where it's triable. That's a wider net than the county-specific rules governing ordinary actions, since it lets a petitioner pick any county across an entire judicial district.

Subdivision (b) supplies the venue rule for the core Article 78 setting — a proceeding against a body or officer. The default there lets the petitioner choose among several anchors within the judicial district: where the respondent made the challenged determination, where the respondent refused to perform the duty at issue, where the underlying proceedings that produced the matter being restrained took place, where the material events otherwise occurred, or where the respondent's principal office sits. A list of exceptions then narrows that choice for particular respondents. A proceeding against a Supreme Court justice or a County Court or Court of General Sessions judge belongs in the Appellate Division of the department where the underlying action is triable, or in an adjoining department's Appellate Division if that department's term isn't in session. A proceeding against a list of specific state officials and bodies — the Regents of the University of the State of New York, the Commissioner of Education, the Commissioner of Taxation and Finance, the Tax Appeals Tribunal (except as provided in Tax Law section 2016), the Public Service Commission, the Commissioner or Department of Transportation for certain matters, the Water Resources Board, the Comptroller, and the Department of Agriculture and Markets — belongs in Supreme Court, Albany County. One further exception loosens that: a proceeding against the Commissioner of Education under Education Law section 4404 may instead be brought in the petitioner's county of residence. A proceeding against the New York City Tax Appeals Tribunal belongs in the Appellate Division, First Department. And a proceeding challenging legislative apportionment belongs in Supreme Court, in a designated county within the judicial department where at least one petitioner resides — New York County for the first department, Westchester County for the second, Albany County for the third, and Erie County for the fourth.

This is the venue map anyone bringing an Article 78 challenge against a state agency needs to check before filing. Getting it wrong for one of the enumerated officials or bodies means the proceeding belongs in Albany regardless of where the petitioner lives or where the underlying event took place.