The policy was a requirement for the party at a school in New Hampshire.
All unvaccinated partygoers had a mark placed on their hands.
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The school superintendent labels it a failed attempt to do contact tracing.
"They fully acknowledge that they should've done a better job of supervising and ensuring that the practices were reasonable," school superintendent David Ryan said.
A review of the event found that marking people's hands may have violated educational and privacy laws.
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