The office of Borough President was created in the consolidation of 1898 to balance centralization with local authority. Each borough president had a powerful administrative role derived from having a vote on the New York City Board of Estimate, which was responsible for creating and approving the city's budget and proposals for land use. In 1989 the Supreme Court of the United States declared the Board of Estimate unconstitutional on the grounds that Brooklyn, the most populous borough, had no greater effective representation on the Board than Staten Island, the least populous borough, a violation of the Fourteenth Amendment's Equal Protection Clause pursuant to the high court's 1964 "one man, one vote" decision.
If it is possible to answer this question, answer it for me (else, reply "unanswerable"): When was the Board of Estimate found unconstitutional?
1989