From the press release announcing the lawsuit:
The Archdiocese of St. Louis and Catholic Charities of St. Louis are taking legal action against the federal government of the United States of America. During a press conference today, Archbishop Robert J. Carlson announced that a lawsuit challenging the legality of the HHS mandate was filed in court this morning.
Archbishop Carlson stated that the Church “had pursued every other imaginable option to correct this problem,” and added that, “Right now the future is unclear, and any scenario that forces us to violate our moral convictions is unacceptable. At the same time, any sce- nario that forces our St. Louis area hospitals, schools, and charities to close would be dev- astating to the many people employed and served by these institutions.”
See the press conference video, posted to the Archdiocese's YouTube channel: