She plagiarized pieces of her last novel, the historical novel "In America" (about the 19th-c, great actress Helena Modjeska) from multiple sources (including a Willa Cather novel), and when caught, she said she was free to do as she liked and that she was stunned Modjeska scholars would object because she was singlehandedly reviving Modjeska from obscurity.
Sontag' defense of her plagiarizing:
"All of us who deal with real characters in history transcribe and adopt original sources in the original domain. I've used these sources and I've completely transformed them. ... There's a larger argument to be made that all of literature is a series of references and allusions.""
That's nice, dear.
She had my dad blacklisted after he wrote a bad review of Fear of Flying.