From this autumn, all employees at state and private schools in Maine must be fingerprinted to enable police to run a criminal background check.
Teachers who refused to be fingerprinted, or who are found to have had a serious criminal conviction, are barred from teaching in the state.
At least two veteran teachers have quit in protest, and 20 have been sacked for refusing to submit to fingerprinting. They are among 58 teachers calling themselves Maine Educators Against Fingeprinting who have started a campaign to overturn the regulation.
The group says the checks are an invasion of privacy, and that there is little evidence that teachers have been paedophiles.
"They're fingerprinting everybody in creation, which is what it feels like up here - tens of thousands of school workers," said Bernie Huebner, a 21-year veteran elementary school teacher who chairs the group.
There are only two recent known cases of sexual molestation in schools in Maine, one involving a scoutmaster, who was also a teacher, and the other a track coach who allegedly abused a student 30 years ago. Neither of the accused had an existing criminal record.