FISA courts were started in the 1970s, but they really were given their power, combined with centralized intelligence collection, with the Patriot Act.
So, all it took was ONE President from the start of the Patriot Act (Obama), and his corrupt fellow-travelers, to abuse the immense power they were given, and prove a grave harm against the Constitution.
The “Patriot Act” was passed into law after the 9-11 attacks. Bush and his band of Statists/Globalists couldn’t pass that POS fast enough.