Final answer:
The Supreme Court decision in Pierce v. Society of Sisters deemed that an Oregon law mandating public school attendance was unconstitutional as it violated the 14th Amendment's protection of educational direction by parents and the operation of private schools.
Step-by-step explanation:
The court decided in Pierce v. Society of Sisters that an Oregon public school law was unconstitutional. The Oregon law in question had required all students to attend public schools, effectively banning attendance at private schools, including parochial (religious) ones. The Supreme Court ruled that this law violated the 14th Amendment by interfering with the rights of parents to direct the education of their children and of private schools to conduct business. The case did not involve the Second Amendment, which concerns the right to bear arms, nor did it directly involve the rights to free speech or assembly as protected by the First Amendment.