Skimpy clothing in the office?

These American models from 1940 know how to dress to impress. But how has women's work wear evolved over the last century? And who were some of the pioneering power dressers who helped shape it?

Casual, chic, Coco. The French designer's stylish suits -- pictured here in 1929 -- were part of a new era of comfortable fashion for women.

One of the world's first supermodels, American Dorian Leigh, wears a cinched-waist jacket from designer Vera Maxwell. In the 1930s Maxwell created the "weekend wardrobe" -- "It was for women who had busy lives, who might travel for their work, and needed ready-to-wear things," said fashion history professor, Rebecca Arnold.

Coco Chanel once dismissed her rival, Elsa Schiaparelli, as: "That Italian artist who makes clothes." Indeed, the designer (pictured right, wearing the "trousered skirt") was known for her whimsical, surrealist-inspired pieces, even collaborating with Salvador Dali.

The Second World War was an interesting time for women's work wear, with many taking on the jobs of men away in battle -- such as the London Underground cleaner pictured on the left, and the bus conductor on the right. Rations also meant luxuries like stockings were in short supply. The center image shows a make-up artist drawing lines on the backs of bare legs, to give the illusion of stocking seams.

The 1950s saw a return to a more feminine style, with designer Anne Fogarty (pictured) leading the way. "Fogarty had the tiniest, tiniest waist, and made all these corseted dresses -- but also was a successful career woman herself," said Arnold. "It was a combination of being very 'housewifey' but also very powerful and dramatic."

It's hard not to think of 1960s office attire without conjuring images of the flawlessly tailored cast of "Mad Men." Here, actress Christina Hendricks' hourglass figure is emphasized with a streamlined dress fitted to perfection. "In the 1960s you have a continuation of the 1950s tailored look -- but breaking it up with more color," said Arnold.

British Airways staff show off their new uniforms in 1977. Over the years, many airlines have commissioned outfits from top designers, such as Yves Saint Laurent for Qantas in the 1980s, Giorgio Armani for Alitalia in the 1990s, and Christian Lacroix for Air France in the 2000s.

Big collars and bigger hair didn't get in the way of Charlie's Angels (Farrah Fawcett, Jaclyn Smith, and Kate Jackson) doing their job in the the 1970s TV series.

Investigative journalist Murphy Brown wore the pants (and the blazer) in 1980s TV series of the same name. This was the decade of the power suit, with everyone from Princess Diana to Margaret Thatcher donning the ubiquitous shoulder pads.

The 1980s also saw a return of fussy ruffles and bows, as seen in this Christian Dior taffeta dress.

In the 1990s, the suit jacket took on a softer look. "It was very understated," said Arnold. "Phenomenally expensive and luxurious, but not really embellished. "

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• A Loyola Law School memo advises students what not to wear to work-study jobs


• Peggy Drexler: Memo implies that women's looks and job performance are related


• She says the memo, while perhaps useful in spirit, was insulting in tone


• Drexler: Does school doubt women's ability to make common sense choices?

Editor's note: Peggy Drexler is the author of "Our Fathers, Ourselves: Daughters, Fathers, and the Changing American Family" and "Raising Boys Without Men." She is an assistant professor of psychology at Weill Cornell Medical College of Cornell University and a former gender scholar at Stanford University. Join her on Facebook and follow her on Twitter @drpeggydrexler.

(CNN) -- Recently, Loyola Law School in Los Angeles issued a memo to its students outlining what not to wear to work-study jobs. For one: low-cut tops. Another: those sexy Louboutins.

"I really don't need to mention that cleavage and stiletto heels are not appropriate office wear (outside of ridiculous lawyer TV shows), do I?" asks the author of a memo entitled "Ethics, Professionalism and Course Requirements for Off Campus Externs" but then goes on to mention it anyway. "The legal community is small in L.A. and judges and lawyers who have unprofessional experiences with externs talk freely amongst themselves about the experiences. It can be embarrassing."

It can also be sexist.

I'm talking about the memo, of course, which offers no such guidelines on appearance for men, if we're to assume that men aren't among those whose cleavage and heels are generating whispers within L.A. courtrooms.

The memo's implication is that there's a relationship between how women look and how well they do their jobs, and that it's okay to judge a woman on her appearance.

It's one thing to acknowledge that a bias exists in society, but quite another to insist on kowtowing to it, and to expectations that are, in most cases, initiated and maintained by men, but not imposed on men.

Women are very often reduced to, or at least measured by, their looks, in every industry, and the message can be infuriatingly contradictory.

Look good, but not too good. Pay attention to vanity, but don't be obvious about it. Be different, but about the same as everyone else.

The Loyola memo noted that the school had received "complaints from supervisors" about students' dress, though it isn't specific about the nature or number of the complaints. While it's possible that some women may go overboard, perhaps the topic could have been addressed with the individual(s) against whom the complaints were filed. After all, overboard is both subjective and confusing. At least one law professor advised women to get ahead by wearing "skirts to appeal to men, makeup to look healthy and competent, and heels to appear more powerful."

What's a constant, though, is that looks matter, and usually that attractiveness pays. So why shouldn't women, who face any number of disadvantages in the workplace, use what they can to get ahead?

According to research by Daniel Hamermesh, author of "Beauty Pays: Why Attractive People are More Successful," the top one-third of attractive females earns about 10% more annually than those in the bottom sixth of the genetic pool. A 2006 study from the University of Helsinki that looked at the role of beauty in politics found that the better-looking the candidate, the more competent, trustworthy and likeable he or she was perceived to be.

When it comes to dress, a recent Harvard Business School study found that dressing distinctly could make a woman appear confident and influential, two qualities especially relevant for courtroom lawyers.

We can't blame Loyola Law School for society's obsession with appearance, and if judges and juries are indeed forming opinions about female lawyers' abilities based on the length of their skirts, it's important for would-be lawyers to recognize that.

It's not right, but perhaps it's a reality. Law in particular is a profession that relies heavily on the opinions and very real biases of others.

That said, we can hold the school responsible for helping to perpetuate the mixed messages women receive about their appearance, and for issuing a memo that, while perhaps useful in spirit, was insulting and condescending in tone.

Loyola is a highly rated law school; it stands to reason that the students accepted there have at least some common sense and social awareness. Presumably there are some brains behind those bodies. By widely issuing the memo using the language it did, Loyola expressed doubt in the abilities of its female students to make their own decisions regarding something as basic as what to wear.

It's important for a school that's in the business of educating women to recognize and support the idea that women can be both smart and attractive; to help shift the conversation from an either/or.

Meanwhile, women should keep pushing the boundaries and resisting definitions, and wearing what they deem appropriate. There was a time, after all, that pantsuits were considered "shocking" courtroom garb, a convention that changed because women insisted it change.

With persistence, eventually what will matter most is how women perform their jobs, and not which shoes they happened to choose that morning.

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The opinions expressed in this commentary are solely those of Peggy Drexler.