One parent of a student who had been excluded, Rosalyn Zucht, sued on the basis that there was not a public health emergency.

[3] Justice Louis Brandeis wrote for the unanimous court that requiring students to be vaccinated was a justified use of "police power" to maintain public health and safety.

[4] Brandeis invoked a previous decision, Jacobson v. Massachusetts (1905), in which the Court upheld the authority of the states to enforce compulsory vaccination laws.

The city of San Antonio, Texas, enacted an ordinance prohibiting any child from attending a public school or other places of education without having first presented a certificate of vaccination for smallpox.

Consequently, Rosalyn Zucht was excluded from both public and private schools due to her refusal to receive a vaccination.