Americans United for the Separation of Church and State has filed suit challenging the City Council invocation policy of Sussex County in Delaware. As far back as 2006, the claim alleges, Council President Michael Vincent has opened official government meetings with a recitation of the Lord's Prayer.

In Mullin v. Sussex County, Americans United asks the court to permanently enjoin the county from sponsoring the Lord’s Prayer or any other sectarian prayers at council meetings.

Americans United filed the lawsuit with the U.S. District Court for the District of Delaware on behalf of four Sussex County residents. All plaintiffs in the lawsuit have attended council meetings in the past and were offended by the governmental body’s promotion of one religious perspective and disregard of the community’s religious diversity.

Legislative prayers that are non-sectarian in nature have been upheld by the Supreme Court as constitutional, but The Lord's Prayer, as the complaint argues (pdf), is "a distinctly Christian prayer."