We tend to glaze over when reading legal jargon, but today's news brings a legal debate that's piqued our interest.

Lululemon, purveyor of expensive yoga pants for taut mommies everywhere, is suing Calvin Klein over their "Astro" pants. But the lawsuit doesn't center on a stolen logo or brand name, as many fashion-on-fashion suits do; instead, Lululemon is accusing Calvin Klein of patent infringement. Lululemon claims Calvin Klein ripped off (so to speak) the "Astro" waistband as well as two other design elements.

Patents are a rare thing in fashion, Fashionista notes, as most patents are utility patents, referring to the function of an invention. Yet design patents refer to the "ornamental aspects of an invention," a distinction that can be hard to pin down. As Susan Scafidi, academic director of the Fashion Law Institute at Fordham University Law School, told the Vancouver Sun:

"Take the average polo shirt, for example. The design isn’t new, so it can’t be patented — novelty being the most basic requirement of patentability — but it’s easy to stitch a logo over the heart and gain instant legal protection, at least for that little crocodile, polo pony, or other trademark."

Thus we see trademark lawsuits all the time (for example, Gucci's court battle against Guess). Design patent court battles? Not so much.

Design patents are hard to obtain in the first place, notes lawyer Adrian Pruetz. "It's very hard to come up with something that's new and that hasn't just been part of the clothing vernacular," Pruetz told the Chicago Tribune, and then it can be hard to protect those designs. But pursuing design patents can be worth it, Scafidi pointed out to Fashionista, if the design element will be used again and again in multiple collections.

Lululemon filed its suit against Calvin Klein and their manufacturer, G-III Apparel, last week in Delaware. Stay tuned to see the outcome... fingers crossed for a highly entertaining, multi-day court battle a la Gucci vs. Guess. That was so fun!

Read more in the Chicago Tribune.

See more designer skirmishes...

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  • Derek Lam vs. Ivanka Trump

    In 2011, designer Derek Lam gave a cease-and-desist letter to Ivanka Trump <a href="http://www.huffingtonpost.com/2011/12/22/derek-lam-ivanka-trump-shoes_n_1165514.html" target="_hplink">accusing Trump of plagiarizing a design from his footwear line</a>, the $780 Ayami sandal. Lam's attorneys gave Trump seven days to pull the shoe from her line. (Courtesy photos)

  • Gucci vs. Guess

    In May 2012, <a href="http://www.huffingtonpost.com/2012/05/21/gucci-lawsuit-gucci-wins-_n_1534491.html#s824190&title=Gucci" target="_hplink">the showdown between Gucci and Guess over the interlocking 'G' logo</a> reached an end in Gucci's favor. Gucci was awarded $4.66 million dollars, a reflection of the profit Guess made from the unauthorized trademark. (Courtesy photos)

  • Pamela Love vs. Chanel

    This year Chanel featured cuffs in their A/W 2012 collection that looked almost exactly like crystal cuffs by Pamela Love from her fall 2011 collection. In a very classy move, Chanel decided to not produce the cuffs, telling Fashionista: "Out of respect for the concerns raised and for the artistic process generally the House has decided not to offer these bracelets for sale as part of the A/W 2012 collection." (Getty/Courtesy photos)

  • Alexander McQueen vs. Snooki

    In March 2012, MTV Style pointed out that one bag in the reality TV star's new collection of handbags was a McQueen knock-off. NOT classy Snooki... (Courtesy photos)

  • Christian Louboutin vs. YSL

    In 2011, the designer of the famous sexy, red-soled shoe Christian Louboutin <a href="http://www.huffingtonpost.com/2011/08/11/louboutin-red-soles-lawsuit_n_924110.html" target="_hplink">requested a U.S. judge to stop the sale of red-soled shoes designed by Yves Saint Laurent</a>. The judge denied the request saying, "Awarding one participant in the designer shoe market a monopoly on the color red would impermissibly hinder competition among other participants." (Courtesy photos)

  • Solange Azagury-Partridge vs. Target

    Target is set to release it's Kirna Zabete designer collaboration collection in September, but there was an accessory in Zabete's collection that looked similar to British designer Solange Azagury-Partridge's lip rings. Although there was no court case involving copyright claims, it is true that these two accessories look very similar to one another. (Courtesy photos)

  • Proenza Schouler vs. Target

    In 2011, Target sold the 'Mossimo Messenger' bag in their stores which Jack McCollough and Lazaro Hernandez of <a href="http://www.huffingtonpost.com/2011/03/25/proenza-schouler-ps1-target_n_840717.html" target="_hplink">Proenza Schouler argued looked too similar to their PS1 bag</a> ($1,600 vs Target's $34.99). The designers were disappointed with Target, having previously partnered with the retailer, to which a spokesperson for Target responded: "It always has been and continues to be the policy of Target to respect the intellectual property rights of others." (Courtesy photos)

  • Madonna vs. Christian Louboutin

    Madonna is lucky to not have a court case slapped on her claiming that one of the shoes in her new 'Truth or Dare' collection is a knock-off of Louboutin's studded stunners. (Courtesy photos)

  • RJ Williams vs. Madonna

    This year, Madonna began her domination of the fashion world (ok, kind of) releasing the first product of her 'Truth or Dare' collection, the 'M' perfume. Unfortunately, <a href="http://www.huffingtonpost.com/2012/05/08/madonna-truth-or-dare-logo_n_1500539.html" target="_hplink">an Australian artist claimed that the singer plagiarized his signature 'M'</a> and sent her a letter, requesting the singer to stop using the symbol. (Getty photo)

  • Shoe Showdown as Louboutin Takes YSL to Court

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