In a letter addressed to Scott, the ACLU said that blocking a constituent is unlawful prior restraint of future speech and deleting posts amounts to "viewpoint-based censorship" in violation of the First Amendment.
"The governor's censorship of constituents' political views violates their free speech rights, undermines public trust of government and offends our democratic values of robust and open debate," said Jay Diaz, staff attorney with the ACLU of Vermont.
Scott spokeswoman Rebecca Kelley defended the practice.
"This is a (Facebook) page for all Vermonters, and it is necessary and constitutionally permissible to have a social media policy that encourages a civil dialogue and protects commenters from being abused, harassed or exposed to hate speech," she said.
The social media policy posted on Scott's Facebook page states it may delete comments and block users who "use profane, vulgar or violent language" or are "disrespectful, hostile or abusive to other users or groups."
Kelley added that they would accept specific recommendations from the ACLU of Vermont to see how they can narrow these provisions.
But Diaz challenged Kelley's assertion that users were blocked for the reasons listed in the social media policy.
"Each of the people who complained to us said that they did not use obscene or vulgar language and were expressing strictly political opinions about gun control," Diaz said.
Scott signed gun restrictions into law this year in the wake of the Parkland, Florida, school shooting and an alleged school shooting plot in Fair Haven, a move that angered many in Vermont's hunting community.
The ACLU has sued governors in Maine, Maryland and Kentucky for similarly blocking constituents on Facebook. A federal court in New York ruled last month that President Donald Trump violated the First Amendment when he blocked critics on Twitter.
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