Internal Revenue Service regulators decided not to ask the Supreme Court to allow them to use the Horse Act of 1884 as a justification for regulating small-business tax preparers, a tacit admission of defeat after two lower courts said the agency exceeded its authority.

In a gift to large tax preparing companies, IRS officials wanted to force independent tax preparers to go through an expensive licensing process. They cited an old statute pertaining to compensation for horses killed during the — wait for it — Civil War as a legal basis for the rule.