A justice of the peace in Louisiana is facing disciplinary action after he refused to marry a mixed-race couple on the grounds that it would not be fair to any children they might have.

Keith Bardwell, a JP for 34 years in Tangipahoa parish, south-eastern Louisiana, turned away Beth Humphrey, 30, who is white, and Terence McKay, 32, who is black. They were the fourth interracial couple to whom he had declined to issue a marriage licence.

Bardwell, who is white, insists he is not a racist and that his decision last week was governed by his concern that mixed-race children were shunned by both white and black communities. He told the Hammond Star: "I don't do interracial marriages because I don't want to put children in a situation they didn't bring on themselves. I feel the children will later suffer."

He told the Associated Press: "I'm not a racist. I just don't believe in mixing the races that way. I have piles and piles of black friends. They come to my home, I marry them, they use my bathroom. I treat them like everyone else."

Bardwell's actions are particularly sensitive in Louisiana, one of 17 mainly southern states that only repealed laws banning mixed-race marriages and relationships when forced to do so by the US supreme court in the 1967 case of Loving vs Virginia. Until then "miscegenation", as it was legally called, was outlawed in many states and was one of the most invasive elements of southern segregation.

In 1883, the supreme court ruled that states were within their rights to ban mixed marriages, finding that this did not breach the constitutional requirement to treat everybody impartially, arguing that white people and black people were punished in equal measure for breaking the miscegenation laws. That ruling stood until the 1967 Loving case.

Humphrey, who left the US military last year, said she was appalled by the JP's actions. "That's blatant discrimination."

The local branch of the American Civil Liberties Union has written to state judicial authorities asking for an investigation and for Bardwell to receive the "most severe sanctions available".

Humphrey and McKay say they will consult the US justice department about filing a discrimination complaint.