The flags of the Confederate States of America represent an entity which broke away from and attempted to overthrow the government of the US.
The flags of the Confederacy represent - as they did in the middle of the 19th Century, and still today - a people fighting to uphold, among other things, the institution of slavery in the United States. In many ways, these emblems have become symbolic of support for slavery itself.
The US has very broad protections of freedom of speech, but there are exceptions. The public display of these flags disgraces ourselves and disgraces our country in the eyes of the global community. They need to be made illegal.