Why was Leo penn blacklisted?

Leo Penn was blacklisted during the McCarthy era due to his involvement in leftist politics and his association with individuals accused of being communists. As a member of the Screen Actors Guild and an outspoken advocate for civil rights, his political beliefs led to scrutiny and eventual exclusion from Hollywood's mainstream productions. This period of intense anti-communist sentiment resulted in many artists facing similar repercussions, limiting their careers and opportunities.