Maine Gov. Angus King defended the state’s teacher fingerprinting requirement as constitutional and fair in a message to lawmakers after vetoing a bill to repeal the law, which is bitterly opposed by the teachers’ union.

As they tried to wrap up business for the session June 21, lawmakers planned to take up King’s veto of a bill to scuttle the law that requires fingerprinting and criminal background checks for all school employees, from janitors to superintendents.

An override seems unlikely. In earlier votes on the repeal bill, neither the House nor Senate could muster the two-thirds majority that would be needed to override the governor’s veto.

In his veto message, King said the fingerprinting law “is a device for prevention, not accusation, and is a uniformly applied requirement for all school employees.” He cited attorney general’s opinions that the law is constitutional.

The governor sought to allay suspicion that teachers are being singled out, saying, “Let there be no doubt that the overwhelming majority of these extraordinary people who serve our children are of outstanding and unblemished character.”

But he said that in any large group, “there are likely to be a small minority who pose a threat to society, in this case, to the very children entrusted to their care.”

King listed himself among the Mainers who have been fingerprinted. He said he was fingerprinted in 1994 before adopting a child–“after I had been a parent for 24 years.”

Maine’s law is opposed by the 25,000-member Maine Education Association and sparked hours of emotional debate in the Legislature. It has prompted some teachers to quit.

The issue arose anew this session after the Criminal Justice Committee demanded to see figures showing how the program was working to determine whether it should be funded.

Last year, both the House and Senate voted to exempt current school employees from Maine’s fingerprinting requirement, but the measure was vetoed by King. The House failed to gain a two-thirds majority needed to override, so the original law remained in effect.