ALBANY – The state Court of Appeals conceded Tuesday that it erred in a June 2013 ruling and reversed itself, determining that an insurer could try to prove in court that a lawyer’s malpractice insurance policy did not cover a $3 million loss.

The court also threw out a 2010 change in the way Nassau County makes refunds to taxpayers in tax certiorari cases, finding that the county adopted the new procedures in violation of the state constitution and state tax law. In another tax matter, the court found that the state’s method for determining residency was flawed.