Mike questions why we should introduce new IP rights in an already competitive market, asserting that "a lack of intellectual property protection actually [benefits the fashion industry]".

While big name designers saw cheap knockoffs hit the shelves quickly, that only helped to drive more innovation. The designers would keep on innovating, trying to outdo each other, while building up their own brand reputation -- which would justify some of the premium they charged for the "genuine article" (quality also plays a role in the price -- the knockoffs generally aren't nearly as well made).

The greatest irony, as discussed in the WSJ article, is that restricting copies may actually harm sales. "If copying were illegal, the fashion cycle would occur very slowly, if at all", which also implies less sales.

The article also discusses some of the challenges of dealing with copyright in fashion.

In other fields, copyright law bars duplicates found to be "substantially similar" to originals. But critics say applying that standard to fashion design would be difficult, and some fear the bill would stifle innovation because designers would constantly worry about being sued. "I don't know how they're going to police this," says Mr. Schwartz of ABS, whose knockoff gowns could be a prime target if the law passes. "This could really damage the creative part of the business if they start putting restrictions on people."

Susan believes copyright should apply.

Fashion design has historically fallen outside the scope of copyright protection because it was considered a craft, not an art, dating back to a time when clothing served to simply cover the body . .  . [but] [t]oday, "fabric is a means of expression, just like pen or ink," she says. 

Of course, copyright protects a specific expression, not a design generally.  The interesting question will be, as Mr. Schwartz suggests, determining what is and isn't infringement, what is a derivative work, and so on.

It's also worth noting that trademark law also has a role in protecting fashion, especially when a designer has a "signature" look or design.