Christian Louboutin's Straratata at left; Jessica Simpson's Evangel at right.

>> Those stories and more in our daily news roundup.

• As if its trademark lawsuit against Yves Saint Laurent wasn't enough to worry about, Christian Louboutin now has to deal with the possibility that Jessica Simpson may have copied his Straratata sandal. [The Huffington Post]
  

• Speaking of copyright infringement: Guess CEO Paul Marciano defended his company against accusations that it's been knocking off Gucci. "I truly believe that if this is something Gucci was genuinely concerned with, they would have acted within days, everywhere," Marciano said in court. "Are you telling me today that suddenly you realize what's happened in 1995?" [The Daily Telegraph]
  

• Barbie is running for president, but not without a little help from Chris Benz. The designer created the campaign wardrobe for the new I Can Be President Barbie doll – which consists of a single suit. "She actually doesn’t have a change of clothes, and she’s not allowed to take those clothes off either," Benz explained. "That’s not what she does." [Styleite]
  

• Dior spokeswoman Charlize Theron is on the May cover of Vogue UK. In the accompanying feature story, she reveals that being a model isn't as easy as it looks. "That f***ing walk, so hard to do," she says of the forceful strut she performed in her iconic J'adore Dior commercial. [Fashion Etc.]

>> It's going to be a big year for Stella McCartney. Her sporty Fall 2012 collection garnered nearly universal rave reviews, and 900 of Britain's finest athletes will compete in her wares during this year's Olympic games in London.

In a recent interview with Tim Blanks, McCartney explained how she's keeping all of her success in perspective. "When I feel myself getting nervous and stressed and self-absorbed, I try to just go, 'Oh, come on,'" she says. A few more highlights from the interview:

On the demise of designers like John Galliano: "I don't think anyone can give an exact reason. Yeah, there's a lot of pressure in our industry. We all feel it. But I think there's a lot of pressure in a lot of industries. Sometimes the fashion industry can get a bit kind of isolated and it's all 'Oooh! It's so relentless!' But I don't see our industry as the only one like that. But I do think that personality comes into play a lot. I also try not to take myself too seriously."

On her famous parents: "Imagine . . . everyone knows who your mom and dad are, and they know something about you and you don't really know anything about them or who they are. So you get a little bit defensive and you sort of want to go up to them and say, 'Hi! Who's your mom and dad?'"

On the death of her mother, photographer Linda McCartney: "I feel like a different person since my mom passed away, like I'm driving a ship with my husband alongside me and we're leading these four children into unknown waters . . . Sometimes I'll get into the bath with all my kids and they'll look at me and say, 'Oh, it's just us! It's just our family in the bath!' And I remember that feeling, when it was just our family. It's such a powerful moment."

On whether she's changed how fashion uses animal products: "I don't think I have, no. But I think I am definitely in the process of doing something very different from other luxury brands. I did always say I wanted to infiltrate from within. That was always my reasoning behind going into partnership with a luxury group that uses a lot of leather in their products. I'm also a real believer that just doing a little something is really a lot better than doing a lot of nothing."

Photo by Craig McDean for Interview

>> Sienna Miller says her sister Savannah is hard at work on a new clothing label, which is her first foray into the fashion business since both siblings left Twenty8Twelve late last January.

"My sister is an amazing designer — she's working on her new label at the moment," Sienna told Vogue UK. "In fact she's designing in my attic as we speak. I just can't wait to wear all of the pieces."

While Sienna didn't say what any of those pieces would look like, Savannah's established aesthetic speaks to a very British sensibility — influenced no doubt by working for other British design talents like Alexander McQueen, Anya Hindmarch, and Matthew Williamson.

The Millers started Twenty8Twelve as co-creative directors in 2007. They left the brand in early January 2012, shortly before they were scheduled to present their Fall 2012 line during London Fashion Week. Sienna, who is currently pregnant, told WWD that she and her sister were "looking forward to new pastures. We wish the brand the best of luck for the future."

Twenty8Twelve has continued as a brand without the sisters' involvement, changing its full name from Twenty8Twelve by s. miller to Twenty8Twelve London.

Savannah, left, with Sienna, March 2011. Photo: Getty