If Julianna Margulies had known that "Canterbury's Law" was going to be on the Fox network, she might never have considered it. Heck, she might never have opened the script.

But there was a little mistake by the executive producer's assistant. The flu-stricken Margulies opened the envelope with the script and a cover letter that contained a typo.

Instead of telling Margulies that "Canterbury's Law" was in development for Fox, the "o" was dropped and she thought the show was for FX.

"I was incredibly excited to do cable," Margulies said. "I had been looking to do a cable show."

"That assistant has since gotten a raise," executive producer Jim Serpico interjected with a smile.

And now the former "ER" star is playing driven defense attorney Elizabeth Canterbury in the new legal drama, which premieres tonight at 7 on Ch. 13. Margulies went out of her way to make it clear she was in no way kidding about how she came to star in "Canterbury's Law."

"It's really true," she said. "And when I read the character, I was like, 'Finally, a character I can play on television.' But, of course, it's cable, so she's dark and it's complicated and she's complex and she's an adult, and I thought she was sexy. And 12, 13 episodes a year — it was a shoo-in. I was very excited."

But when she called to say she was in, she was almost out just as quickly. "They're like, 'FX? It's Fox,"' said Margulies, who instantly began to reconsider "because 22 episodes a year is brutal for everyone."

And she knows whereof she speaks after starring as Carol Hathaway on 134 episodes of "ER." She didn't leave that show because she was unhappy with the work, she was just burned out.

"Actors need to replenish. We're not machines. So, to keep coming up with that energy and creativity, you may not see it on the screen, but when everyone else's day ends, yours goes on for another four hours in preparation for the next day."

So she "thought long and very hard, and I kept saying, 'No' because of the 22" episodes a year thing if the show gets picked up for a full season. Finally, after meeting with the producers and Fox Entertainment president Peter Liguori — as well as a "great dinner" and "a few martinis" — Margulies signed on.

"It was too good to pass up," she said.

Margulies stars as Elizabeth Canterbury, a strong-willed defense attorney who has a penchant for taking on lost and/or unpopular cases. And she's not above playing rather fast and loose with the legal rules in the pursuit of justice — she is indeed dark and complicated.