Marcy Kahn, who has been a prosecutor, a law firm partner, a criminal judge and an appellate justice over a 30-year career, will retire from the First Department in September to become an advocate on climate change, sustainable development, human rights and the rule of law.

Her departure will leave the First Department four judges short unless Gov. Andrew Cuomo makes his judicial selections before the fall. A fifth vacancy will be created when Justice John Sweeny Jr. retires at the end of the year.