As yet, there is no case law applicable to these issues.
Having multiple non-marital partners, even if married to one, is legal in most U. jurisdictions; at most it constitutes grounds for divorce if the spouse is non-consenting, or feels that the interest in a further partner has destabilized the marriage.
Some Jews are polyamorous, but mainstream Judaism does not accept polyamory; however, Sharon Kleinbaum, the senior rabbi at Congregation Beit Simchat Torah in New York, has said that polyamory is a choice that does not preclude a Jewishly observant and socially conscious life.
La Veyan Satanism is critical of Abrahamic sexual mores, considering them narrow, restrictive and hypocritical.
Kerista was a new religion that was started in New York City in 1956 by John Peltz "Bro Jud" Presmont; throughout much of its history, Kerista was centered on the ideals of polyfidelity and creation of intentional communities.
Some bigamy statutes are broad enough to potentially encompass polyamorous relationships involving cohabitation, even if none of the participants claim marriage to more than one partner.
In most countries, it is legal for three or more people to form and share a sexual relationship (subject sometimes to laws against homosexuality or adultery if two of the three are married).
Accordingly, they include parallel entitlements, obligations, and limitations.
Among the latter, as in the case of the New Zealand Civil Union Act 2005, there are parallel prohibitions on civil unions with more than one partner, which is considered bigamy, or dual marriage/civil union hybrids with more than one person.