Egbert v. Lippmann
United States Supreme Court
104 U.S. 333 (1881)
Egbert (plaintiff), assignee of a patent on corset springs invented by Barnes, sued Lippmann (defendant) for infringement. Barnes had made and used the invention for more than two years before filing the patent application, but the use was limited to one person and was generally hidden from public view inside the fabric of the corset itself, with only a small number of witnesses seeing the springs when they were transferred from an old corset to a new one. The trial court found this constituted invalidating prior public use, ruling for Lippmann.
Whether disclosure of an invention limited to one item, shown to one person, and generally concealed from public view constitutes public use sufficient to invalidate a later patent.