The wall between church and state is one of the most powerful and enduring images in American law, but as a metaphor it fails to capture the complicated and porous relationship most Americans have to the expression of religion in public life.

On Wednesday, for the first time in 30 years, the Supreme Court will reconsider the contours of that relationship in the legislative setting when it hears oral argument in Town of Greece v. Galloway. While the court has previously upheld prayers before legislative sessions, the details of the current case differ in important ways.

Officials in Greece, a town of about 100,000 in western New York, invite local clergy members to deliver a prayer before monthly town board meetings. In theory anyone may lead the prayer, but in practice prayers were exclusively Christian for nine years. Many used language like “in the name of the Lord and Savior Jesus Christ, who lives with you and the Holy Spirit, one God for ever and ever.”

Two residents sued the town under the First Amendment, arguing that the prayers were unconstitutionally sectarian, and that people are coerced into participating in the prayers when they have to attend board meetings, which include public hearings, votes on proposed ordinances and the swearing in of new town employees.