Mirroring numerous real-life scandals, The Good Wife speaks directly to the question so many people have as they look at the latest sad-faced woman standing mutely at a podium beside her supposedly sorry politician husband (here played by Sex And The City's Chris Noth): what on earth can be going through her head?
"I just loved how complicated Alicia is as a woman," says 43-year-old Margulies. "This is someone who thought her life was going one way for many, many years. She trusted that life and felt secure in that world. Then everything around her began to crumble."
It was a situation that seemed made for TV, she says. "As an actor, I knew this woman allowed me so many places to go," Margulies says. "I could peel her like an onion for years to come, because her reactions wouldn't be predictable."
Margulies has followed many of the real-life cases that her show evokes, and relishes the chance to explore the situation via fiction. "I was so quick to judge all those women I saw standing up by their men," she says. "I kept thinking, 'Well, why are you standing there?' Now I get to answer those questions on TV."
She has her own ideas about why these wives don't leave. "These are smart women," she says. "Look at Hillary Clinton. It's not like these are silly little wallflowers. Most of them have two degrees. They're incredibly accomplished. Why they stay with these men is a good question. I think it boils down to the fact that we just don't know what is going on in the bedroom or at home."
In other words, the cheating is only part of a story to which the public is rarely privy. "I don't think anyone should ever cheat," she says, "but we're all human beings. I've had friends whose husbands have cheated on them, but they're still together because they have three children and they see their fault in it too."
There are a good many highly placed political women nowadays, so why is it that it's usually the political men who are having affairs – or, at least, who are getting caught? "Honestly, I think the women are all exhausted," she laughs. "Women just don't have the time, between the kids and the job and the cleaning and the cooking!"
Margulies is the youngest of three daughters. Her mother was a dancer in the American Ballet and her father an advertising writer. The family moved around the globe, with stints in Paris and the UK, before settling in New Hampshire. Margulies majored in art history at Sarah Lawrence College in Bronxville, NY, and, after performing in college plays, decided to focus on acting.
She made her screen debut in Out For Justice (1991), and in 1994 was cast as Nurse Hathaway on ER. She would play the role for six years, be nominated for the Emmy Award as Outstanding Lead Actress in a Drama Series six years in a row and win once, in 1995.
Earlier this year she returned to ER for two episodes, including the series finale. It represented closure for a chapter of her life, she says, especially since her ER co-star and onscreen romantic interest George Clooney also returned for the last episode.
"Everything was very quiet," she recalls, "because we couldn't say that George was coming back. I never said a word, even to my parents. When I got there on the set with him, it felt very cocoon-like and wonderful.
"The only problem was the medical jargon," says Margulies, who had deliberately avoided medical roles in the years after she left the series. "It just wouldn't come off my tongue. It was horrible. But it was really fun to go back. George and I had a great three days. It was a wonderful way to say goodbye to a great era."
Last year, she started a new chapter in her own life, giving birth to her son, Kieran.
"I took a little time after I had my baby," she says. "What's different now is that I am a mom and a wife, which means that I need to stay in one place, so TV is perfect. I love working, and I've found that the richest characters I can find are on TV."
The Good Wife begins tomorrow on Channel 4, 10pm
This article was first published in Scotland on Sunday on 24 January, 2010