"Law & Order" (search) has been fighting off the competition for 15 seasons - constantly updating itself as it picks up and sheds a string of talented actors from Michael Moriarty to Jerry Orbach to Jill Hennessy to the latest addition, Dennis Farina.
But it doesn't get any easier.
"This is the biggest competition any of our shows have ever faced," says "L&O" creator Dick Wolf (search).
"The closest was ["Law & Order] Criminal Intent" versus "The Sopranos," Wolf recalls. "But that was broadcast versus cable. This is two major networks with their biggest shows. It's going to be interesting."
This fight has been brewing for months. Wolf got in the first shot by calling "Law & Order" a brand and "CSI" a franchise - meaning that his shows were each different but linked by the "L&O" style, while "CSI" was simply a single formula with a new cast and a new city for each spin off.
Wolf, 57, insists he wasn't trying to malign the Jerry Bruckheimer-produced smash hits.
"I hope it didn't sound like I was coming out swinging," says Wolf. "Jerry [Bruckheimer] and I have known each other since we were in advertising."
Then he repeats the zinger.
"We have a brand; they have a franchise," he says. "I didn't see it as a negative or a positive for either show. With 'CSI,' you know what you're getting. It's the No. 1 drama in the country. Clearly they know what they're doing."
Clearly, "L&O" knows what it's doing as well. Farina - a former cop whose big break was the '80s hit "Crime Story" - steps in tonight as Det. Joe Fontana for Orbach's Lennie Briscoe.
"Dennis Farina is going to amaze," says Wolf, who jokes that Farina is quite convincing as a cop.
"This is completely self-serving," says Wolf, "but it's the best work he's ever done. It's as seamless a transition as when we went from Michael Moriarty to Sam Waterston. He's either the 19th or the 20th cast member.
"Jerry said six or seven years ago, if it was the same ongoing cast, the show wouldn't still be on the air."
Facing "CSI: New York" - with its own star power - Wolf wanted to keep some familiar faces, especially since Orbach would be gone.
"Liz Rohm [who plays Assistant DA Serena Southerlyn] will be leaving sometime during the season," says Wolf. "She really helped us out of a jam because her movie career has taken off. With Dennis Farina coming here, I told her, 'I'd really love to have you here [at the start].' I said, 'Please stay here for part of the season.'"
No matter how the ratings battle turns out, there is no chance there won't be a few versions of "Law & Order" on the air into the foreseeable future.
Next up, "Trial By Jury," may be the most different of the four "L&O" shows yet, says Wolf. Unlike the others, which focus strictly on law enforcement and the prosecution, this show - set to debut sometime after New Year's with Orbach in a supporting role - will, for the first time, include the point of view of the defense. "I shouldn't be telling you this," says Wolf, "but I already know what the fifth one is going to be. I can't wait to do it."