After a court ruling against dancing at national memorials, a group protested this weekend by dancing at a national memorial. Now arrests at that demonstration are under investigation.   Some said U.S. Park Police officers actions were inappropriate and that the officers used too much force. Five silent dancers they were listening to music with earphones and dancing at the Jefferson Memorial Saturday were arrested and charged with demonstrating in a restricted area. The memorial was shut down for about 15 minutes. In April 2008, about 20 people participated in a similar flash dance that organizers said was a celebration of Thomas Jefferson, the author of the Declaration of Independence. Mary Oberwetter was arrested on misdemeanor charges of failing to follow police orders and interfering with operation of the memorial. Oberwetter fought the charges, arguing that low-key dancing was protected free speech. The courts agreed with the U.S. Park Service that it must maintain decorum at national monuments and that the dancing was a demonstration, which is banned inside the nations memorials. Earlier this month, the U.S. Court of Appeals agreed.