How DC comics supervillain Joker has become rated-R

The Joker has been around since the first Batman comic book in 1940. But you won’t see Batman in the film ‘Joker,’ which stars Joaquin Phoenix and opens this week.
This is the first R-rated film for a DC-created franchise since “Watchmen” in 2009. The Joker of the modern times is a lot darker than that of the 1950s-1980s. Sixty-five years ago, a book titled “Seduction of the Innocent” by psychiatrist Dr. Fredric Wertham created a public frenzy and result