The American Civil Liberties Union (ACLU) of South Dakota said the state “stifled” the free speech of Lyndon Hart when it refused to approve his application for a ‘REZWEED’ plate on the basis it was “in poor taste”.

Mr Hart runs a business called Rez Weed Indeed, which supports and promotes the legal selling and use of medical and recreational marijuana on Native American reservations.

Stephanie Amiotte, ACLU of South Dakota legal director, said: “The First Amendment prevents arbitrary decision-making when it comes to expression.

“Although no one likes to be offended, it’s dangerous to allow the government to decide which speech is allowed and which should be censored.”

The federal lawsuit is expected to succeed as various US courts have previously struck down laws similar to South Dakota’s.