When I read Orin Kerr's post about the NYTimes' alarmist reporting on the Department of Homeland Security's request for Census data about Arab Americans, I initially thought that from a "let's put 'em in internment camps" perspective, data about Muslims would be more useful than data about Arabs. After all, a couple of the most publicized terror cases, such as that of Jose Padilla, have involved people of non-Arab ancestry. Without casting aspersions on Islam, it seems fair to say that there are no non-Muslims in Al Qaeda, while there are plenty of non-Arabs (converts, South and Southeast Asians, etc.). Bin Laden is no racist -- any man who rejects degenerate Western culture and rejoices in sharia law can join the jihad!
However, the Census Bureau couldn't provide information about Muslims even if it wanted to do so:
Limitation of the Data--Although some experts consider religious affiliation a component of ethnic identity, the ancestry question was not designed to collect any information concerning religion. The Bureau of the Census is prohibited from collecting information on religion. Thus, if a religion was given as an answer to the ancestry question, it was coded as an "Other" response.
The prohibition originates in Public Law 94-521, a bit of legislation passed in 1976, which provided for a mid-decade census of population. The law "[e]liminates the penalty of imprisonment for refusing or willfully neglecting to answer questions asked on a census questionaire [and p]rovides that a person may not be compelled to disclose information regarding his religious beliefs or membership in a religious body."
When one cannot discriminate on the basis of race, generally one is also legally prohibited from discriminating on the basis of religion, but not of, say, politics. Thus religion's status is more similar to race -- an immutable characteristic -- than to political and other chosen preferences. This holds true socially as well; the average American feels much freer to mock and disparage people of different political viewpoints than he does to mock and disparage people of different religions.
So the Congressional ban on the Census's gathering information on religion in the same way it can gather racial data is surprising. Why should disclosing my ancestry be mandatory, but disclosing my religion be categorized as an "Other" response?