118 U.S. 356 (1886), argued 14 Apr. 1886, decided 10 May 1886 by vote of 9 to 0; Matthews for the Court. During the summer of 1885, many Chinese in San Francisco, including Yick Wo, violated a municipal laundry ordinance to test its validity. This local law allowed only the city's Board of Supervisors to approve laundry operating licenses. Failure to secure a license and continuing to do business could result in a misdemeanor conviction, a thousand-dollar fine, and a jail term of up to six months. The ordinance did not apply to laundries located in brick buildings.
This ordinance was clearly aimed at Chinese businesses since Chinese laundries were invariably located in wooden buildings. The law followed several other attempts by San Francisco to discourage Chinese settlement. In 1870 the Cubic Air Ordinance restricted the number of occupants in Chinese apartment buildings based upon certain space requirements. The Queue Ordinance of 1876 stipulated that all Chinese prisoners had to have their hair cut, and the No Special Police for Chinese Quarter Ordinance of 1878 denied Chinatown police protection. In addition, Chinese laundries had to pay a special fee if they used horse-drawn delivery vehicles.
The laundry ordinance was also drafted with white Californians’ concern about the Chinese presence in mind. From 1820 up to 1882, the year the first Chinese Exclusion Act was passed by Congress, open immigration brought many Chinese to California. In 1880 approximately 75,000 Chinese lived in California, amounting to 10 percent of that state's population. Nearly half of California's Chinese were concentrated in the San Francisco area.
According to an 1881–1882 labor census taken in San Francisco, Chinese were primarily employed in four businesses: making cigars, shoes, and clothes, and operating laundries. Most laundries in San Francisco were owned by Chinese. Yick Wo had lived in California since 1861 and had been in the laundry business for twenty-two years. His laundry had been inspected by local authorities as late as 1884 and found safe. But in 1885 the Board of Supervisors denied him and two hundred other Chinese laundry owners their licenses. Only one Chinese laundry owner was given a license, and she had probably not been identified as Chinese. The Board was obviously seeking to wipe out the Chinese laundry business.
After Yick Wo was denied his license, he continued to operate and was arrested. In police court Yick Wo was found guilty, and fined ten dollars. He refused to pay and was ordered to jail for ten days. Yick Wo then petitioned the California Supreme Court for a writ of habeas corpus. The petition was denied, and he appealed to the U.S. Supreme Court, naming the sheriff, a man named Hopkins, in the suit.
Yick Wo claimed that the ordinance abrogated his Fourteenth Amendment rights because of the blatant discriminatory results of its implementation. He presented statistical evidence showing the discrimination to San Francisco's Chinese community. Only 25 percent of San Francisco laundries could operate under the Board of Supervisors’ licensing requirements, seventy-nine of them owned by non-Chinese and only one owned by a Chinese. His attorneys also contended that the ordinance violated China's 1880 treaty with the United States. San Francisco argued that the Fourteenth Amendment could not infringe upon the police powers granted to cities and states.