For some reason, I found a reference to an early patent on Ouija boards, and with a bit of digging, came up with this page of Talking Boards Patents and Trademarks. Most of these early patents declare it a game, rather than a legitimate way to contact the dead.

Using pat2pdf, I extracted a few of these patents as PDF files:

Becker, 1880

Patent 233,198

Bond, 1891

Patent 446,054, the first patent to mention the term “Ouija”

Fuld, 1892

Patent 479,266, makers of Ouija boards until the bottom fell out of the market in the 1970s

It appears that patent examiners of the past were every bit as diligent as those we have today.