Under the provisions of the New York Constitution of 1938, re-apportioned in 1953, 58 Senators and 150 assemblymen were elected in single-seat districts for two-year terms.

In 1964, the U.S. Supreme Court handed down several decisions establishing that State legislatures should follow the One man, one vote rule to apportion their election districts.

Senators John H. Hughes and Lawrence M. Rulison (both Rep.) questioned the authority of the federal court to shorten the term of the 1964 electees,[1] alleging excessive costs for the additional election in an off-year.

The court also held that, although the constitutional State Senate apportionment formula provides for additional seats, the increase from 58 to 65 was unwarranted.

The approximate party strength at this election, as expressed by the vote for Judge of the Court of Appeals, was: Republicans 3,106,000; Democrats 1,824,000; Liberals 208,000; and Conservatives 207,000.

The Legislature met for the regular session (the 189th) at the State Capitol in Albany on January 5, 1966;[10] and adjourned on July 6.

[12] On February 23, the Court of Appeal appointed a commission of five members to map out new districts because the Republican-majority Senate and the Democratic-majority Assembly could not agree on a new apportionment.

The commission was chaired by President-elect of the American Bar Association Orison S. Marden, of Scarsdale, who was not affiliated with any party and was deemed politically independent.

Jerome Schutzer, Anthony B. Gioffre, Theodore D. Day and James F. Hastings changed from the Assembly to the Senate at the beginning of the session.