Laws prohibiting polygamy are constitutionally defective in USA

http://www.marriagedebate.com/2006/01/polygamy-meme-continuessouthern-voice.htm
"What about polygamy?" an audience member inevitably asks Eyer, executive director of the ACLU of Utah. "Will gay marriage lead to legalized group weddings?"
Each time, Eyer answers affirma­tively.
"The ACLU of Utah has traditionally advocated that personal relationships between consenting adults are protected by the Constitution, and that freedom of religion and freedom of expression are fundamental rights," Eyer says, citing the her ACLU chapter's official stance on polygamy since 1989.
"Criminal and civil laws prohibiting the advocacy or practice of plural marriage are constitutionally defective," she adds. "Neither the polygamists nor the proponents of same-sex marriage are wild about the analogy, but we do see the two as similar concepts." . . .
"If you convert marriage to merely the placing of a license on consenting adults that are in a committed relationship, or who love each other, then there is no logical line that can be drawn between gay marriage and polygamy," [Matt] Staver says. "Gay marriage clearly opens the door to polygamy."