Editor's note: Since the original publication of this post, we've heard from Susman's managing partner Neal Manne. His comments are now included in the post.

Big Law must believe that lawyers are hopeless romantics. Why else are they selling the fantasy that lawyers can make oodles of money, do cutting-edge work and spend as much time as their heart desires on babies and leisure?

I'm talking about those eye-popping perks making headlines. No, I don't mean gourmet snacks, yoga breaks or free dog-walking services. I'm talking about unlimited vacations and unlimited parental leaves—benefits that take lawyers away from what they are put on earth to do: create billable hours.

Unlimited vacation policies are proliferating like bunnies across the Big Law landscape. Among major firms that offer this goody: Cadwalader, Wickersham & Taft; DLA Piper; Gibson, Dunn & Crutcher; Kirkland & Ellis; Latham & Watkins; Mayer Brown; Orrick; White & Case. (You can check out Chambers for a more comprehensive list.)

Not to be outdone, litigation powerhouse Susman Godfrey upped the ante last fall by offering unlimited paid (!) leave for new parents—male or female and you don't have to be the primary caregiver—in addition to its unlimited paid (!) vacation leave.

So how's the unlimited parental leave working out? (I'm going to assume that people don't have the chutzpah to indulge in months and months of paid vacations.)

Just beautifully, say Susman lawyers who spoke to Law.com's Dan Packel recently. The lawyers using the leave policy “depict a firm culture that appears diametrically opposed to the depictions in recent lawsuits targeting Morrison & Foerster and Jones Day, where women who returned from maternity leave allegedly found their work environment changed dramatically,” Packel writes

I don't doubt that Susman's uber-generous parental leave policy makes fabulous headlines, but can we get real? Seriously, does anyone really think an associate can take a long leave (say a year or more) at the firm's expense and not pay a price?

First of all, Susman is not exactly some laid-back, lifestyle firm. It's an intense, high-stakes litigation boutique. It's also incredibly profitable, hauling in $2.585 million in profit per equity partner. And it makes a point of beating Cravath, Swaine & Moore in associate pay. (Last year, first-year associates started at $195,000 and got a median bonus of $110,000.)

Not to be crass, but firms are in the business of making money. As profitable as Susman is, what firm can afford to shell out big salaries to nonbillers, especially if a critical mass of new parents opt for extended tours of diaper duty? I think there'd be a partners' revolt.

Susman's managing partner Neal Manne doesn't completely disagree: “We are very much a for-profit enterprise. But my view as managing partner is that in the medium and longer term our business success depends on continuing to attract and retain the absolute very best associates.”

Manne insists that the firm's paid vacation and leave policies “are not gimmicks.” He adds: “We really mean it and our associates know we mean it. It works because we know that our associates are responsible and reasonable. They work very hard. They do fantastic work. They allow our firm to succeed the way it does—no.1 litigation firm in the country for seven consecutive years, according to Vault. We have a unique business model and a unique group of associates. Maybe our policies wouldn't work at other firms but they do at Susman Godfrey. That's our happy reality. Our policies are here to stay—and we hope our associates are, too.”

That said, Manne agrees lengthy leaves entail compromises. “Realistically, if someone took off an entire year then, of course, they would be delayed by a year for partnership,” adding, ”we haven't had someone take off a year.”

“It's all about economics,” says Betiayn Tursi, who heads Women in Law Empowerment Forum, an organization that promotes women in the legal profession. She adds that if a lawyer is taking off a big chunk of time and wants to remain on partnership track, “you need an honest assessment of their chances of making partner. Without that, all bets are off.”

Karen Kaplowitz, an adviser to Working Mother's Best Law Firms for Women Initiative, says, “Some research, not law firm specific, suggests that more than six months of leave can actually hurt women professionally.” She says firms need to monitor the careers of women who take extended leaves to see if such policies are working. “Women lawyers will only believe they can take longer leaves and make partner when firms share success stories of parents who have done that—and help new mothers do the same.”

So far, such success stories are rare. Why then do firms offer these tantalizing goodies?