LOS ANGELES (CBS / AP) — A ban on the sale of foie gras that went into effect in California this week is being challenged in court.

A Canadian exporter of the duck liver delicacy, a foie gras producer based in New York state and a Southern California restaurateur filed a lawsuit in Los Angeles Superior Court Monday seeking to invalidate the new law, which prohibits products derived from force-fed birds.

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Their lawyers are claiming the ban is vaguely written, so broad that it also applies to skins, feathers and other by-products of ducks raised primarily for foie gras, and violates the U.S. Constitution’s commerce clause by affecting companies from outside California.

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The California Legislature passed the ban on producing and selling foie gras in 2004, but the law only went into effect on Sunday.

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