Oregon's Catholics and their allies decided to carry on the fight in the courts, but they needed help to do that. They looked to the National Catholic Welfare Conference for that help. Located in Washington, D.C., the Welfare Conference had evolved out of the National Catholic War Council. The Welfare Conference's founders were convinced that Catholics from dioceses all across the country still needed an organization to mobilize their power and speak with a single voice on issues of national import even after the war had ended. Some Catholics both in Rome and the United States were skeptical. The Vatican had fought battles with the French and other nations for centuries over attempts to create national versions of the church and did not now want an "American church" making claims for its own, special, national privileges. Some American bishops were also wary of a national organization trying to tell them how to run their dioceses or claiming to speak for them to the Pope. Bishops in Michigan had even refused the NCWC's help in their successful fight against the Klan. Yet the Archbishop of Portland, Oregon, Alexander Christie, had fewer resources and confronted a more powerful enemy. He needed the NCWC is he were going to keep the state's Catholic schools in business.

The Oregon School Case proved to be an important turning point in the NCWC's history. After taking on the case in January of 1923, the Welfare Conference began raising money - $60,000 by September of 1923; created a National Catholic School Defense League; and, with a blizzard of press releases and pamphlets, launched, what historian Thomas Shelley has called, "probably the most extensive, the most professional, and the best conducted" public relations and press campaign "ever attempted by the Catholic Church in America up to that time." The Council also hired William Guthrie, a distinguished New York lawyer often mentioned as a candidate for the Supreme Court, to join with the Portland Archdiocese's lawyer, J.P. Kavanagh, to argue the case. The NCWC's performance in this fight quieted its critics and helped prove the organization's contention that the Church in America needed a national office to defend and advance its interests.

On December 22, 1923, lawyers working for the Archbishop of Portland asked for an injunction against the Compulsory School law on behalf of the Society of the Sisters of the Holy Names of Jesus and Mary, an order of Catholic Women Religious, who ran several schools in Oregon. They did not argue for the injunction on the basis of the First Amendment, the right to freedom of religion. Rather, they argued on the basis of the Fourteenth Amendment that the Compulsory School Law would force private schools to close and thus deprive their owners, like the Sisters of the Holy Names, of their property without due process.

In January of 1924, a three-judge panel (see photo above) heard the case and on March 31, 1924 granted an injunction against the State of Oregon ordering it not to implement the law. The state appealed the case to the Supreme Court. In June of 1923, the Supreme Court had struck down Nebraska's bill prohibiting private elementary schools from teaching foreign languages. In March of 1925, the Court heard the Oregon case of Pierce vs Society of Sisters and on June 1, 1925, overturned the Oregon school law.

Since that decision the Court has heard many cases concerning the government's relations with parochial schools. In 1930, it up held a Louisiana law permitting the state government to supply textbooks to private schools, arguing that such support advanced a public good. In 1947, the Court approved the right of a state or city government to pay for buses to transport children to private schools. The Court, however, refused to sanction "released time" schemes that would permit public school children to attend religious instruction under church auspices in their schools during school time. Some people, including the former President of Harvard, James B. Conant, would continue argue as supporters of the Oregon School Law had that all children should attend public schools for, at least, some of their school years to ensure the nation's democratic unity. Never again, however, would a state challenge the right of private schools to exist, and never again would the Supreme Court retreat from its defense of that right.