This is so incorrect, it's funny. There was no Federal law prohibiting polygamy in Joseph Smith's day, (those came a short time later - prompted precisely because of the Mormons), but every State had laws against adultery.
Adultery was defined as a man having sex with a woman other than his wife (singular). Just as todays laws say nothing specifically about gay marriage, it has always been prohibited (until the time that we are forced to address it).
Mormons were forced from State to State during Joseph Smith's time, not because they were jealous of his "revelation," but because of the practice of the aberrant multiple 'wives.'
Wait a second. I say, “In that day, there was no law in the United States against polygamy.”
You say, “This is so incorrect, it’s funny. There was no Federal law prohibiting polygamy in Joseph Smith’s day...”
Please, you’re confusing me.
~”...but every State had laws against adultery.”~
Fine. Smith has multiple wives. Adultery is sex -outside- of legal marriage, however that marriage is defined. Your subsequent statement is today’s definition - not that of 150 years ago. I’m sorry, it just doesn’t wash.