In 1908 the supreme court ruled in Muller v. Oregon that

Curt Muller, the owner of a laundry business, was convicted of violating Oregon labor laws by making a female employee work more than ten hours in a single day. Muller was fined $10. Muller appealed to the Oregon Supreme Court and then to the U. S. Supreme Court, both of which upheld the constitutionality of the labor law and affirmed his conviction.