Officials at W. Tresper Clarke High School in East Meadow say the dog, Simba, could pose a danger to other students, Newsday reported.
"I don't think they know what they're doing," John Cave, 15, said. "I think they're going to be in big trouble with the state."
Cave arrived at the school Tuesday with his mother, twin sister, lawyer and Simba. They left after a brief conversation with at the door with Principal Timothy Voels, who had a sign-language interpreter with him.
Paul Margiotta, the lawyer, said school officials say the state Human Rights Division's decision is not enforceable unless a court orders Simba's admission. The district plans to appeal the division's finding.