This is what's tricky. By all accounts the show started as a reboot of ER. However when you look at ER compared to The Pitt, apart from the first episode, they both fall into the "medical drama" category. The Pitt could just as easily be sued by any other medical drama.

But! The first episode of ER is VERY different from the what you think about when you think about ER. The first episode, which is where Crichton is the credited writer, more closely resembles what you might consider The Pitt. It's comparing 1994 TV to 2025 TV but... Mayyyyyyyyyyyybe? (In my opinion, no.)

But let's look at Noah Wyle. At a high level the character of "John Carter" went from a new doctor to an expert doctor. You could at face value say the character of "John Carter" from ER is "Michael Robby Robinavitch" from The Pitt and just changing the name isn't enough.

Except! Doctor Carter has a rich history in Chicago. Doctor Robby is from Pittsburgh, or at the very least has zero connection to Chicago. Doctor Robby is Jewish. Doctor Carter is not. Doctor Carter is rich. Doctor Robby is not (by comparison).

The only similarities between Doctor Carter and Doctor Robby is that they are both "good doctors" played by Noah Wyle.

This lawsuit has some merit. Which is to say it has more than zero merit. Is that number higher than one percent? No. Probably not.