Why was Arthur miller blacklisted

Arthur Miller had been blacklisted himself by Hollywood, when he declined to testify before the House of Un-American Activities Committee (HUAC).

Explanation:

During 20th Century Arthur Asher Miller was a controversial figure in American theater also an American playwriter and essayist. His one of the plays named "Death Of A Salesman" was sent to Elia Kazan according to him it was "a great play" and the character of Willy Loman reminded him of his father. Later the play was accorded by prestigious Tony award and Pulitzer prize.

Their friendship was very highlighted in late 1940s and early 1950s but later Kazan's testimony to the HUAC cracked their relationship. Miller broke with Elia Kazan over his decision to provide the House of Un-American Activities Committee (HUAC) with names of former members of the "American Communist Party".