[1] Caveats were instituted by the U.S. Patent Act of 1836, but were discontinued in 1909, with the U.S. Congress abolishing the system formally in 1910.
A caveat expired after one year, but could be renewed by paying an annual fee of $10.
[2][3] Caveats were similar to provisional applications used today in the United States Patent and Trademark Office (USPTO) which also expire after one year.
According to the Guide to the Practice of the Patent Office 1853,[4] the primary objective of a caveat was to prevent the issuing of a rival patent for the same invention to a subsequent inventor.
Before the issuing of a patent, the caveats filed within the preceding year were searched.