No senior men's or women's World Cup has ever been played on synthetic turf, and a group of top international women's players would like to keep in that way.

About 40 players, headlined by the last two FIFA Women's World Players of the Year — American Abby Wambach and German Nadine Angerer — has retained legal counsel to fight plans to play the 2015 FIFA World Cup on synthetic turf. Canada is hosting the 2015 Women's World Cup, and all six match venues, including BC Place in Vancouver, feature synthetic turf.

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According to The Equalizer, a site devoted to covering women's soccer, the lawyers hired by the players — one firm from the United States and one from Canada — sent a letter to Canada Soccer and FIFA officials last week stating that the use of an "inferior" surface for the Women's World Cup "is discriminatory and violates Canadian law."

The letter, which was obtained by The Equalizer, argues that use of "a second-class surface is gender discrimination that violates European charters and numerous provisions of Canadian law, including human rights codes and the Canadian Charter of Rights and Freedoms."

This is just the latest chapter in the players' fight against synthetic turf. Back in March 2013, Wambach told The Equalizer: "We’ve worked so hard as female athletes — not only here in the United States, but internationally — to grow the game and, in my opinion, I think this is taking a step back. All of the men’s international players around the world would argue the same point. A lot of these guys will not play on an artificial surface because it is an injury-prone surface, and I don’t blame them.”’

Germany coach Silvia Neid weighed in last year, as well, saying playing soccer on synthetic turf is "just not possible," and likened the players to test animals by having them play on it.

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Canada is currently hosting the U-20 Women's World Cup. Many of those matches are being played in stadiums with synthetic turf. One stadium, BMO Field in Toronto, features natural grass.

Speaking at a press conference at that event, FIFA president Joseph Blatter said the synthetic turf isn't going anywhere.

“There was a time that playing on so-called artificial turf, grass – it was a nightmare,” Blatter said. “It was a nightmare because there was not the quality; it was just a carpet put on concrete, as they played at a certain time in the North American Soccer League in the ‘80s. But now the quality of the turf, or the artificial grass, has improved very much, and it is definitely – it is the future.”

The 2015 Women's World Cup matches will be played on FIFA Recommended 2 Star, considered "the highest playing performance for professional-level football."

As Athletic Business' Paul Steinbach detailed in this September 2012 article on FIFA's program for certifying synthetic turf performance, a 2 Star field exhibits a softer touch on the professional slide-tackler's skin, whereas a 1 Star field is built to endure the near-nonstop pounding of multiple youth and adult leagues.

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FIFA has spent years honing its certification practices for synthetic turf. Using highly specialized instrumentation, FIFA-endorsed labs test everything from a fiber's melting point to a finished field's interaction with players' feet.

And Blatter says players should get used to the surface.

“This is for the future,” he said. “If now there is a category of players or coaches, they are not used to this new technology, which is this turf. They say at the first instance, they say it’s not good. But it’s good.”

Michael Gaio is eMedia Editor of Athletic Business.