NUT delegates voted for all unproven allegations against teachers to be removed from Criminal Record Bureau checks.
A union representative said allegations were showing up on records years after they were made when teachers applied for new jobs, even though schools and the police had found there was nothing to investigate.
The NASUWT voted to ballot members to refuse teaching pupils when one made a serious false accusation and was not excluded.
"Some zealots believe an accused teacher is guilty no matter the evidence,"
Mike Wilson, a secondary teacher from Nottingham, said.