France is considering a law that would ban Muslim girls from wearing (the required) headscarves at public schools. In the interest of fair treatment, also banned would be "ostentatious" or "large" crosses, crucifixes, yarmukles and the Star of David.
Of course, what is "large" or "ostentatious" is always open to interpretation. While a headscarf or yarmukle are obvious, what exactly is a "large" cross? Are they going to have officials inspecting jewelry with rulers?
It's unlikely that this sort of thing could happen in the United States, but this is the sort of law that people like Barry Lynn of Americans United for the Separation of Church and State and the litigious Michael Newdow would like to pass.
The courts (as is demonstrated almost daily by the Ninth Circuit) cannot be trusted to maintain religious liberties -- instead we have to depend on the legislative branch.
If the Supreme Court should completely lose its mind and rule in the Newdow case that the words "under God" in the Pledge of Allegiance constitutes an establishment of religion, then you will see a Constitutional Amendment passed in record time.
We don't have the same widespread hostility to religion here that is the norm in France -- and for that we should be grateful.