J.K. Rowling's third update to The History of Magic in North America — a collection of short stories meant to provide background for the Harry Potter prequel film Fantastic Beasts and Where to Find Them — focuses on the divide between the magical and non-magical communities in the United States.
Set in the late 18th century, "Rappaport's Law" is about an unfortunate episode that occurred while Emily Rappaport was president of the Magical Congress of the United States of America (MACUSA), the American equivalent to the Ministry of Magic. The incident in question involved Dorcus Twelvetrees, the daughter of Rappaport's Keeper of Treasure and Dragots (American wizarding currency), who fell in love with a No-Maj named Bartholomew Barebone and caused a historic breach in wizarding world secrecy.
After a series of horrible events — including the persecution of many witches and wizards — resulted from Dorcus's leak of magical information, the President was forced to institute Rappaport's Law, an edict implementing complete segregation between those with magical powers and those without. The mandate ended up becoming a defining difference between the American and European wizarding communities, as no laws governing relations with No-Majs to that degree existed in the "Old World."
The fourth part of the series will go live at 2 p.m. GMT on Friday.