What is the meaning of “there's no line between the two”?

Question

In Drama film/Biography film The People vs. Larry Flynt (1996), Preacher,Jerry Falwell filed a case on Larry Flynt, Hustler Magazine, in supreme court for potraying his image in satrical parody way in Hustler magazine. So Justice Scalia said this words after hearing Alan Isaacman, Larry Flynt's lawyer words.

Alan: I saw a political cartoon that's over 200 years old. It depicts George Washington, riding on a donkey, being led by a man, and the caption suggests this man is leading an ass to Washington.

Justice: I can handle that. I think George can handle that. But that's a far cry from committing incest with your mother in an outhouse. I mean, there's no line between the two?

Alan: Uh... No, Justice Scalia. There is no line between the two. Because what you're talking about is a matter of taste, not law.

What is the meaning of "there's no line between the two"?

Answer 1

I can see where you might be confused with the saying

there's no line between the two

Usually, it might mean there no *difference** or boundary between two things especially when referring to right and wrong.

However, in your example, I believe Scalia is saying

there is no connecting line between the George Washington cartoon and the Falwell cartoon

that the Washington cartoon has nothing to do with the Falwell cartoon.