They can’t. Basic logic and facts are hard to refute. This is why Canada already has a movement to legalize polygamous marriage. I expect things to follow suit here.
With a Supreme Court like ours, it is inevitable.
The waters are being tested by things like “Sister Wives.”
One of the NatGeo ‘Taboo’ shows had a “polyamorous” group featured recently.
Every time I’ve asked another female if she’d marry a guy who openly said, “I’m bi-sexual,” that female has said no.
Polygamy will be legalized in this country when some bi-sexual sues for the right to marry his boyfriend and his girlfriend. There is no longer any legal basis to stop them.