by Hal Bookbinder
Where in the U.S. may a man marry his niece?
Jewish Law (#83-#100 of the 613 commandments, refer to http://www.jewfaq.org/613.htm) describes prohibited relations, including with one’s mother, step-mother, aunt, sister, step-sister, sister-in-law, daughter, step-daughter, daughter-in-law, granddaughter and step-granddaughter. But, there is no prohibition on marrying one’s grandmother or niece.
All 50 U.S. states ban marriages between a man and his niece with one exception. Rhode Island law (§ 15-1-4) permits such marriages, but only among Jews! This law exempts Jews from consanguinity restrictions in state law so long as the relationship is permitted by Jewish law.
Rhode Island Statutes on Domestic Relations (refer to http://www.rilin.state.ri.us/statutes/):