I think the Constitutionality will really depend on exactly how a law or policy is worded. So, for example, banning all jewelry (which would include a cross necklace) would probably be fine. But I would love to see some info about a law that said it's OK to explicitly ban religious articles when similar secular articles are allowed.
I think the modern interpretation is of the "slippery slope" argument about how extreme it might get. For the most part school districts might decide on an individual basis about what crosses the line into advocacy rather than simply passive displays. Most of these laws were actually anti-Catholic. I've heard that nuns used to teach in public schools, and that many of these laws were enacted as an anti-Catholic measure.
There certainly have been complaints, but there's a distinct lack of prosecutors willing to prosecute.
Here's Pennsylvania's law:
http://www.legis.state.pa.us/cfdocs...&smthLwInd=0&act=14&chpt=11&sctn=12&subsctn=0
Section 1112. Religious Garb, Insignia, etc., Prohibited; Penalty.--(a) That no teacher in any public school shall wear in said school or while engaged in the performance of his duty as such teacher any dress, mark, emblem or insignia indicating the fact that such teacher is a member or adherent of any religious order, sect or denomination.
(b) Any teacher employed in any of the public schools of this Commonwealth, who violates the provisions of this section, shall be suspended from employment in such school for the term of one year, and in case of a second offense by the same teacher he shall be permanently disqualified from teaching in said school. Any public school director who after notice of any such violation fails to comply with the provisions of this section shall be guilty of a misdemeanor, and upon conviction of the first offense, shall be sentenced to pay a fine not exceeding one hundred dollars ($100), and on conviction of a second offense, the offending school director shall be sentenced to pay a fine not exceeding one hundred dollars ($100) and shall be deprived of his office as a public school director. A person thus twice convicted shall not be eligible to appointment or election as a director of any public school in this Commonwealth within a period of five (5) years from the date of his second conviction.
Apparently Nebraska recently repealed its law.
http://journalstar.com/legislature/...cle_81e1879c-e55e-55ef-85a4-ea97c639b7bb.html
The Legislature on Thursday repealed Nebraska's longtime ban on public school teachers wearing any religious garb in the classroom, ending the bill's long journey through legislative roadblocks erected by Sen. Ernie Chambers of Omaha.
Chambers made a final effort to waylay the bill (LB62), but his motion to return the proposal from its final reading stage to an earlier round of floor consideration was rejected before the measure was enacted on a 39-5 vote.
This is the law that got repealed:
http://nebraskalegislature.gov/laws/statutes.php?statute=79-898
http://nebraskalegislature.gov/laws/statutes.php?statute=79-899
79-898.
Public schools; religious garments; wearing by teachers prohibited; penalty.
Any teacher in any public school in this state who wears, in such school or while engaged in the performance of his or her duty, any dress or garb indicating the fact that such teacher is a member or an adherent of any religious order, sect, or denomination, shall be deemed guilty of a misdemeanor, and upon conviction thereof be fined in any sum not exceeding one hundred dollars and the costs of prosecution or shall be committed to the county jail for a period not exceeding thirty days or both.
79-899.
Public schools; religious garb prohibited; enforcement; violation; penalty.
In case of violation of section
79-898 by any teacher employed in any public school, notice of which having been previously given to the school board or board of education employing such teacher, the board shall suspend such teacher from employment in such school for the term of one year. In case of the second offense by such teacher the board shall disqualify permanently such teacher from teaching in such school. Any member of a board who fails to comply with the provisions of this section is guilty of a Class V misdemeanor and upon conviction shall be punished by a fine not exceeding one hundred dollars and costs of prosecution.
