On a day when most Americans celebrate a high holiday of Christianity, my thoughts turn to Muslims, who we recently learn have had their houses of worship subjected to warrantless searches to look for the presence of radioactive materials through the use of remote sensing devices. Under a case written by Justice Scalia (Kyollo v. U.S. (2001)), the use of infrared sensing technology to look through the walls of a house and detect heat lamps used to grow marijuana is an unreasonable search under the Fourth Amendment. So it would seem closely analagous to search a mosque with a Gieger counter or a similar device used to detect radiation.
Now, Kyollo was decided 5-4, and some might think that recent changes on the High Court suggest a reversal is in the works. But both the late Chief Justice and retiring Justice O'Connor voted in the minority in Kyollo. My link in the title is an article by one of my intellectual heros, Eugene Volokh, who suggests that while searching for drugs using such a device may be "unreasonable" under the Fourth Amendment, searching for radioactive materials may not be. After all, the harm in cultivating, and presumably selling and using, some marijana plants pales in comparison to the harm that would come from the creation of a nuclear bomb.
The level of intrusion involved in a search like this would be minimal, it is true, since normal background radioactivity (the kind that occurs in nature, or that is emitted from digital watches or other electronic devices using radioactive decay for power) is ignored. A search for radioactivity is narrowly-focused on exactly the crime in question and to that extent seems reasonable, as Professor Volokh suggests. And, I suspect that most Christians would say, "If my church were scanned with a Gieger counter by the FBI, I wouldn't have any problem with that." Whether they would have a problem with scanning the church with an infrared sensor, which could detect a variety of activites, is a different issue.
But it's still a "search" and whether a search is reasonable or not is something that requires a case-by-case examination. Thus the requirement that law enforcement authorities obtain a warrant before, or at minimum immediately after, conducting a search. What makes a search reasonable is not only whether the search is narrowly-tailored to finding specific evidence of a specific crime. It also involves suspicion of criminal activity occurring in the first place. To suggest that warrantless searches of mosques for radioactivity are reasonable, one must accept that any mosque can reasonably be suspected of having radioactive materials stored within. This I do not accept as a reasonable proposition.
I think that law enforcement may take into account the content of political rhetoric coming from those who preach at a mosque without violating anyone's civil rights. I think that if there is other objective evidence that suggests that a mosque might be used for a criminal purpose, then the fact that it is a house of worship provides the structure and its inhabitants with no special, elevated constitutional protection. And while it's true that most terrorists who pose a threat to the United States are Muslim, the converse proposition is simply not true.
Objective evidence giving rise to at least a reasonable suspicion of a crime must be present in the first place before a warrant can be issued -- and the fact that the structure is used for a disfavored religion is not objective enough evidence to justify a search. Law enforcement searching a house of worship cannot help but have a deterrent effect on people who seek to worship there, no matter how unobtrusive the search may be. And if Muslims are not free to worship without being searched by law enforcement authorities, then neither are Christians or Jews or Buddhists or Zoroastrians. So if there's some reason to think that a particular mosque might be used for this purpose, a search warrant should issue. But if there's not, these people should be left alone to worship in peace and solitude.