Every Slave State in the USA had Slave codes during the period in which slavery was legal. These slave codes were legal codes regarding the owning of slaves, much the same as laws regarding real-estate (they were very similar). Since slaves were treated as property the basic human rights that applied to other American's did not apply to them, in fact, any slave marriages that occurred meant absolutely nothing in the eyes of the law as property technically cannot marry (think of it like a fork marrying a spoon, except worse because these are people).
Some slave codes even made it illegal for slaves to be educated. In regards to assembly, slave codes would not allow for assembly of slaves outside of mandatory assembly (chain gangs, ect.)
Hope this helps!
