On May 10, 1886, the U.S. Supreme Court unanimously found that the San Francisco Board of Supervisors had administered in a racially discriminatory fashion a city ordinance requiring laundries to obtain fire safety permits.
San Francisco passed a health and safety ordinance in 1880 requiring that all laundries in wooden buildings get the board's approval for the safety permits and operating licenses. Of the city's 320 laundries, 310 were constructed of wood, and 240 of those were Chinese owned. However, all of the Chinese applicants were denied safety permits, while only one non-Chinese applicant was turned down.
Although Yick Wo had lawfully operated his laundry for 22 years before the new ordinance took effect, he was arrested in 1885 by Sheriff Peter Hopkins for refusing to pay a $10 fine for operating the business without a license. He was jailed one day for each dollar of the fine and the case was raised on a habeas corpus writ.
After the California Supreme Court found that the city's supervisors had acted within the scope of their authority, the case was taken to the U.S. Supreme Court on a writ of certiorari.
Famously stating that the San Francisco law had been applied "with an evil eye and an unequal hand," (Yick Wo v. Hopkins, Sheriff,
118 U.S. 356 (1886)), the high court's ruling established two precedents: that discriminatory enforcement of a facially neutral law violates the equal protection clause of the Constitution's 14th Amendment, and also that the clause protects all persons and not just citizens.