A three-judge court panel ruled Wednesday that a World War I memorial in the shape of a cross in Bladensburg, Maryland, is unconstitutional, a decision that a legal scholar says could imperil other similar memorials. In a 2-1 decision, the U.S. Court of Appeals for the 4th Circuit said the 40-foot cross erected 92 years ago violates the First Amendment’s Establishment Clause. “The monument here has the primary effect of endorsing religion and excessively entangles the government in religion,” Judge Stephanie Thacker wrote for the majority. “The Latin cross is the core symbol of Christianity. And here, it is 40...