Radiation Surveillance:

Apropos Orin's post, two thoughts:

(1) The argument that the police can't aim radiation surveillance devices at homes (and likely businesses, mosques, and the like) without a warrant is a nontrivial one: It's basically Kyllo v. United States (no aiming heat sensors at homes without a warrant) meets Mincey v. Arizona (no special Fourth Amendment exceptions for investigations of very serious crimes). I discuss this in this Slate piece from 2002.

My ultimate conclusion is that such radiation surveillance from outside the buildings should be constitutional, because what's an "unreasonable search" when looking for drugs (or even for evidence of murder) becomes reasonable when looking for radiation weapons: "[F]inding dirty bombs must simply be different from fighting normal crime. Searches for weapons of mass destruction can't be treated like searches for marijuana-growing devices or even for murder weapons." Others have argued that it might be constitutional for another reason -- searches that are likely to reveal only evidence of contraband (which, the argument would go, includes searches for radioactive materials but not for heat sources) don't invade any reasonable expectation of privacy; I'm not as wild about that theory, but I agree with its bottom line. Nonetheless, I think the Slate piece may help explain the nature of the argument that such searches are unconstitutional.

(2) Orin points out that "In numerous cases, the monitoring required investigators to go on to the property under surveillance, although no search warrants or court orders were ever obtained, according to those with knowledge of the program." I want to caution people against assuming that going onto the property under surveillance without a warrant is per se unconstitutional under existing law. There are various reasons why entering the property wouldn't itself be treated as an unconstitutional search, for instance if the parts of the property that they entered was generally open to the public, or if the property was the urban equivalent of "open fields" as opposed to the inside of someone's building (or the "curtilage" of that building).

Some of these doctrines are quite complex and unsettled, and I don't want to go into them in detail here; and I also want to stress that even if entering the property wasn't a search, doing some things on that property (perhaps including measuring radiation, or perhaps not, see item 1 above) may well be a search. But people should realize that whether "go[ing] on to the property under surveillance" is unconstitutional without a warrant is a difficult question.

Idealist (mail):
In my law school moot court final, the fact pattern was the same as Kyllo (then in the district court). Justice Kennedy asked me a hypothetical question that basically posed the question here: can the government conduct warrantless searches by electronic means for nuclear material inside a home. I do not remember my answer, but I remember that he was unimpressed by it. At the reception following the competition, he told me that I had missed the obvious answer. Sadly, he never told me what that answer was, and I still do not know.

If the search would only detect material in such quantities that they could not legally be present in a home, the cases on drug dog searches would seem to make the search OK. If the search would detect perfectly lawful activity (this was the situation in Kyllo), then under Kyllo, it would be illegal. I do not think the claim that the the searches detect only "waste" gamma rays is any more valid than the Government's argument, rejected by the Kyllo court, the infrared searches only detected "waste" heat.

Of course, a different rule might exist in exigent circumsatnces (but that does not seem to be the case here). Further, it seems to me that Kyllo does squarely apply to public buildings--religious or not--where the expectation of privacy is different.
12.23.2005 4:55pm
Tom Holsinger (mail):
The law here can be pretty weird. California courts have held that persons may be convicted of being drunk in public if they are in the front yards of their home homes, even if the yard is fenced, provided the fence has a gate and the gate is open at the time.

I have no idea what the federal rules on the meaning of public access or public space.
12.23.2005 4:59pm
Defending the Indefensible:
What is their major objection to getting warrants?
12.23.2005 5:01pm
Anderson (mail) (www):
Leaving aside my ignorance of just what innocuous stuffs might exude gamma rays, I've gotta side with EV on this one. Nukes are a clear and present danger, if you like, in a way that drugs just ain't. I realize that kind of argument can be abused, but nukes are several orders of magnitude beyond most other threats.
12.23.2005 5:02pm
Adam S (mail) (www):
Regarding "searches that are likely to reveal only evidence of contraband" radiation monitors are likely to reveal more people undergoing radiation therapy than dirty bombs. (Simply because of the relative prevalance of such people.) I know you didn't build your analysis on that, but I'm curious if you think that it changes anything?
12.23.2005 5:17pm
Dan1 (mail):
My main problem is the standard slippery slope argument. It seems that every time the gov't gets a power like this, it's simply a matter of time before it's used against drugs.
12.23.2005 5:19pm
Andy Treese:
I also had a similar moot court problem for this year; the issue in that case was detection of a wireless computer network emanating from a home. Even after Kylloa, isn't there a fair argument that the use of the radiation sensors isn't a search in the first place, by distinguishing geiger counters and radiation sensors as being "in general use" where the "thermtron" system wasn't? (It's a stretch , but bear with me.)

In Kyllo, Justice Scalia refers to the Thermtron system twice (including in the holding) as "Technology not in general use," applied to gather details from the home which could otherwise not be obtained without a warrant. It makes sense if you approach the Katz test - 1) subjective expectation of privacy and 2) that XoP is one which is objectively "reasonable" (that is, the XoP is one which society is prepared to accept). I think Kyllo implicitly stands for the principle that society will always find "objectively reasonable" an expectation of privacy from technology which it is neither aware of nor fully understands. Consequently the use of such technology to constructively enter the home will always be a "search" which may then be assessed for reasonableness.

If that reading is right, the question remains whether the Court would be willing to distiguish cases based upon technology "in general use" and if so, what test or standard would they use?

In our case, we distinguished on the grounds that wireless computer networks are in general use, and members of the public who turn on such networks either know (or should) that their existence can be detected from outside the home. Certainly a similar argument exists in the "radiation detection" context - while not everybody understands how geiger counters work, it's fair to say that most folks have a general notion that radioactive materials can be detected based upon... well... the very particles that make them radioactive.

I'm not sure how far this argument would fly - I tend to err on the side of "rule it a search, then assess for reasonableness." There's also a problem to be addressed when society is aware technology exists, but not the degree to which it has been advanced by the government. Is "radiation sensing" technology in general use when everybody knows geiger counters exist, but not how sensitive or precise they are?
12.23.2005 5:22pm
Andy Treese:
Good grief. Bear with the typos; clearly the name of the case is "Kyllo."
12.23.2005 5:23pm
snead16 (mail):
Idealist . . . Justice Kenedy's "easy answer" was that anything that can be detected "radiating" from a home through electronic means that do not physically intrude into the home is fair game for the feds.

The problem here, is Kennedy was in the dissent in Kyllo.

So, really, his easy answer is not the "right" answer -- yet.
12.23.2005 5:24pm
Andy Treese:
And, evidently, I should've read Prof. Kerr's thread just below this one. Disregard - I think he said it much better.
12.23.2005 5:31pm
Are there public safety issues with radiation emissions that are not present with heat emissions from a house? For example, if you have a device that is emitting radiation into the public space, are you increasing the likelihood that your neighbors will develop cancer?

Also, I'm no scientist, but I think there is a significant scientific difference between radiation detection and the kind of monitoring in Kyllo. If radiation comes through the walls of a house and hits the pavement on a driveway, then would a detection device later aimed at the driveway show evidence of radiation exposure?
12.23.2005 5:49pm
The Original TS (mail):
Regarding "searches that are likely to reveal only evidence of contraband" radiation monitors are likely to reveal more people undergoing radiation therapy than dirty bombs.

Except the stuff you'd need to make a dirty bomb is way, way hotter than people undergoing radiation therapy. Radiation therapy doesn't turn people into walking radiation hazards. If you're detecting cancer patients sitting at their kitchen tables when you drive by on the street, your detector is far too sensitive. In fact, I question whether it's technically feasible to detect a cancer patient with a mobile detector from 50 meters.
12.23.2005 5:55pm
Kent Scheidegger (mail) (www):
Regarding the comment that radiation monitors would detect people undergoing radiation therapy, I don't think so. Most radiation therapy involves exposure at the hospital and does not make the patient radioactive at all. Some types involve ingestion or implantation of radioactive material, but the levels involved are vastly lower than would be involved with a "dirty bomb" or other terrorist weapon.

In Kyllo, the balanced was tipped by the danger that thermal imaging more sophisticated than that actually used in the case could reveal private but legal information. I don't see that danger here.
12.23.2005 6:01pm
Michael B (mail):
"My main problem is the standard slippery slope argument."

Life and reality in general is a never ending slippery slope; death alone provides stasis. So in terms of the law, unless the subject is archaic, highly marginal or virtually inconsequential laws, the "slippery slope" argument is little more than a tautology since every law of any consequence is an attempt to come to terms with life's slippery slopes.
12.23.2005 6:13pm
cfw (mail):

"What is their major objection to getting warrants?" No probable cause so no warrant obtainable.

The problem with an "its all ok" response is it allows too much. What are the limits? Is it ok to geiger houses? Is it ok to enter a mosque after hours to geiger? If it is a "national security" exception to the 4th, what rules out a break in? If Nixon went into Watergate to geiger, with reason to believe the place had a pound of yellow cake, would that be ok?

Seems to me one must have a "reasonable suspicion" test and a requiremnt of "reasonable procedures" - sort of like urinalysis for soldiers allowed to handle nukes (done without warrants, based on reasonable suspicion, with prescribed reasonable procedures).

Breaking into a mosque to geiger may make sense and be legal in extreme circumstances, but not routinely. Risks of improper profiling based on race or religion must be considered.

More globally, why are the authorities not openly doing more to round up nukes and nuke materials in places like Russia? Hopefully they are active but covert. I am pleased to see something being done to protect against threats from nukes. I doubt that what is afoot is anywhere near enough, but who knows, the CIA has $41 billion per year and could be spending some large chunk of that making deals to obtain nukes and nuke materials (keeping them out of the hands of Iran, N Korea, OBL, etc.).
12.23.2005 6:27pm
Tom Holsinger (mail):
Original TS,

Check out this story about "the radioactive Boy Scout" who built a home-made breeder reactor in a back yard shed. The neighbors were mighty surprised when NEST teams in full moon suits started parading through everyones' yards.
... After the moon-suited workers dismantled the shed, they loaded the remains into 39 sealed barrels that were trucked to the Great Salt Lake Desert. There, the remains of David's experiments were entombed with other radioactive debris.

"These are conditions that regulations never envision," says Dave Minnaar, radiological expert with Michigan's Department of Environmental Quality. "It's simply presumed that the average person wouldn't have the technology or materials required to experiment in these areas."

David Hahn is now in the Navy, where he reads about steroids, melanin, genetic codes, prototype reactors, amino acids and criminal law. "I wanted to make a scratch in life," he explains now. "I've still got time." Of his exposure to radioactivity he says, "I don't believe I took more than five years off my life."
12.23.2005 6:30pm
The Original TS (mail):

Yes, I recall that story from a few years ago. IIRC, his "experiment" was detectable with a hand-held geiger counter from half a block away. Stuff for a dirty bomb would be much more radioactive and much more concentrated. The point is, though, that you can't pick up cancer patients from half a block away using a hand-held geiger counter.
12.23.2005 6:55pm
Illinois v. Caballes, rather than Kyllo, is more likely to control the issue. "Radioactivity" is probably a lot more like "odeur de dope" than infrared.
12.23.2005 7:01pm
Adam S (mail) (www):
Kent, TS,

The New York City subway radiation detector pilot picked up medical doses. See, for example High Security Trips Up Some Irradiated Patients, Doctors Say (I recall the story when it was in the NY Times.)

A detector, once authorized, will be tuned to "slightly above background radiation." After all, if the bad guys have shielded their stockpile, then a detector that will detect the stockpile will also detect anything else slightly above background, like medical uses. (Or, heck, a stack of smoke detectors, which contain Americanium. EPA radiation information contains a bunch of useful information. I haven't dug into the numbers and emission rates to figure what would be detected at what levels of sensitivity.)
12.23.2005 7:23pm
Dave Hardy (mail) (www):
Thought--might there be a distinction between that which forms an image and that which does not? If that seems like a strange distinction, consider:

1. Imaging infrared requires a warrant. Waste heat argument fails. Too close to "this magic device will see right through your walls" (which IR won't, but can be used to very roughly substitute).

2. As noted above, sniffing dope on the breeze does not require a warrant. More like plain sight, or should we say, plain smell. Ditto for city code inspectors sniffing something they don't like. Or FCC radio direction finding to pin down a pirate radio transmitter.

Or might the difference here be reasonable expectation of privacy? If something smells, you shouldn't expect no one to notice it, and if you transmit, you know you can be heard.

In either event, I think geiger counters land on the permissible end of the spectrum. They don't image, just signal that gamma rays are flying around. A person with a load of radioactive waste should appreciate that it is detectable by sensors at a distance.
12.23.2005 7:26pm
John Lederer (mail):
Technically isn't an off premises geiger counter measuring nasty things you are sending my way? Alpha and beta particles.

Sort of like seeing snowballs lofting over your fence.
12.23.2005 7:50pm
Former Navy Nuke:
Kent, T.S.,

Medical doses are definetely detectable, but probably not from across the street. A dirty bomb or lab may or not be either, depending on what they are using and how smart they are...
12.23.2005 8:14pm
Former Navy Nuke:
Please read the second sentance as ... may or MAY not be either...
12.23.2005 8:15pm
Tom Holsinger (mail):
Origina TS,

They don't use hand-held geiger counters. When you drive or walk through downtown DC, look for the little dome-shaped thingies on small pedestals on the sidewalks and street corners. Don't mess with those or you will shortly find yourself in a small room with some rather unsympathetic people.

Those thingies sent alerts about people who recently taken some radioactive iodine to determine how active their thyroid is. While they were driving down the street.
12.23.2005 8:17pm
The Drill SGT (mail):
I'm surprised I guess that this is news to people. I live in the DC area and folks know that there are radiation monitors on the incoming highways, within the metro system, etc. I think most folks would not have it any other way after 9/11. To find out that we have vehicle mounted gamma rad detectors making drive by's of locations of interest on a regular basis seems within my level of civil liberties threshold of pain, considering the alternative. The detectors after all could only detect what should not be there under any circumstances.

As someone said earlier in the week: For the President not to have employed radiation monitoring, given the potential downside risk, would seem to be an impeachable dereliction of duty, not the reverse.
12.23.2005 8:22pm
Wintermute (www):
I don't want to redefine "unreasonable" as EV seems to. Prohibition started the gutting of the Fourth Amendment. The War on Drugs is finishing the job. Now the War on Terror (another unending war) will just about finish the disembowelment.

A sniffer picks up rads. Either it's strong enough and localized enough to get a search warrant, or they need to get closer, onto the private property in question (someone else's property, you got not standing, so they say). Why not radio in for a warrant and have it faxed to the van? Otherwise, just as a practical consideration, and these are important too, you got a van full of feds in some church parking lot after hours, someone comes out, maybe weapon in hand, asking them to leave. Some of these national security types have a VERY superior attitude and feel licensed to use extreme force when challenged.
12.23.2005 8:56pm
triticale (mail) (www):
It should be noted that the parallel in drug enforcement is not the aroma of either the plants or the smoke, but the heat and electrical consumption of the halogen HID lights commonly used in serious grow ops. My understanding is that heat and electric consumption are not generally considered sufficient basis for a warrant without other evidence. In any case, the cost and spectrum suitability of high efficiency LED grow lights is improving rapidly enough as to render this particular issue out of date.
12.23.2005 9:21pm
The NJ Annuitant (mail):
I am having trouble finding a valid privacy interest in the air outside of the private enclosure. Radiation is, I think, a projection from the source to the outside. I do not see why a warrant is needed to test the air, unless the testors enter the property of the suspect.
12.23.2005 10:24pm
The Original TS (mail):
There are two different things going on. Stationary monitoring and mobile monitoring.

" At its peak, they say, the effort involved three vehicles in Washington, D.C., monitoring 120 sites per day, nearly all of them Muslim targets drawn up by the FBI."

This is what I was referring to and what Orin mentioned in his original post. I don't think this kind of thing needs a warrant, per se, though I'm troubled that some of the monitoring involved actual trespass. But that's a different issue.

The stationary sensors must be analyzed differently. For one thing, they can pick up cancer patients but that is because the cancer patient can pass within a few meters of the sensors. I'd analyze these sensors similarly to video cameras monitoring public streets. One thing I think that undercuts a lot of Fourth Amendment problems is that, unlike the "search" of a specific building, no one knows who the passers-by are. So even if the sensors can detect radiation from a cancer patient, there's little if any privacy invasion. Also, while the sensors can detect this kind of radiation, they can also tell the difference between this and a nuclear threat. There appear to have been some difficulties with this in the early days but I haven't read of all that many radiology patients being wrestled to the ground on the National Mall lately.

Medical doses are definetely detectable, but probably not from across the street. A dirty bomb or lab may or not be either, depending on what they are using and how smart they are...

I'd disagree. If you've got enough stuff to make an effective dirty bomb it's going to be a)potent and b) a decent volume of material. It'd have to be pretty amazingly shielded to have the same radiation levels as a cancer patient. Remember, you know that a weak signal 50 meters away is a proportionally stronger signal at the source.

Second, and this is a bit technical, you can measure the decay products and they'll look different depending on what the original radioactive substance was. No need to go into much detail here but all radiation is not alike. Plutonium, for example, produces a distinct signature so if you're using a sophisticated monitoring device, you're unlikely to confuse a dirty bomb with a cancer patient.

I'm out of here now. See y'all after the holidays. Merry Christmas!
12.23.2005 10:50pm
David Pittelli (mail) (www):
Medical doses are definetely detectable, but probably not from across the street.

Depends on the use. When a person is irradiated (External beam radiation therapy, the most common type, or very short-term implants which are removed after minutes of treatment), he does not himself become radioactive. If he is implanted with radioactive "seeds," these are generally emitters of short-range alpha or beta particles, whose radiation is stopped by less than a centimeter of flesh. It is only in cases of injected liquid radionuclides, if they are gamma emitters, that one might emit significant amounts of radiation outside of one's body.

12.23.2005 11:32pm
The Drill SGT (mail):
The Original TS,

While you are right on most of your analysis, you make one over simplification.

If I were to make a fission device, I'd be using Plutonium or enriched Uranium. You are correct that those have different emission signatures than medical radio substances.

HOWEVER: If I were really just doing a dirty bomb, e.g. conventional explosives with a radio wrapper, then I quite possibly might use the same sorts of low grade medical radio substances (but in higher quantities) thus the shielded signature might well be similar to a cancer patient at long range.
12.23.2005 11:34pm
mls (mail):
EV says: ?It's basically Kyllo v. United States (no aiming heat sensors at homes without a warrant) meets Mincey v. Arizona (no special Fourth Amendment exceptions for investigations of very serious crimes)."

Maybe it is Kyllo meets Mincey meets dicta in Florida v. J.L. Recall that in J.L. the court rejected a Mincey-like argument that tips about weapons possession lowered the reasonable suspicion standard because of the dangerousness of guns . . . The court noted that it did not need to reach the issue of whether such weakening of RS would be justifiable of the tip was about a bomb. . . .
12.24.2005 1:27am
exfizz (mail):
Um, I just came to this topic late and IANAL, but IAAP ("I am a physicist" (retired)) and thought I'd chime in with three observations:

(1) It is correct that different radionuclides produce different types of radiation that a sophisticated detector could distinguish.

(2) Geiger counters are non-directional. I'm long out of the business, but IIRC, it is very difficult to "image" high-energy radiation. But you don't need to.

(3) Key point: Several posters have missed an important point that causes them to think incorrectly about the problem of the nearby cancer patient and the faraway dirty bomb.

Radiation intensity I falls off as r-2. So it is true that 10kg of Bad Stuff 100m away (dirty bomb) "looks" the same as 1g of Bad Stuff 1m away (cancer patient).

But by taking two measurements at different distances from a suspected source you can distinguish between the two. [er, pause... scribble…] The absolute distance r to a source is easily determined by taking two simple "Geiger-counter" style measurements from different distances: then r=2dr/((I1/I2)-1). Given r you can determine the source's effective size. Do this twice and you can triangulate the source's precise location.

Summary: Simply walking/driving around with a simple detector you can locate a radioactive source and classify it as small or large. A slightly more sophisticated detector will tell you what the radionuclide is.
12.24.2005 2:18am
Kevin L. Connors (mail) (www):
This is a terribly interesting dilemma. It is built upon the premise that one's right to privacy ends where one's actions intrude upon the public domain. But, in this case, we are talking about a region of the public domain (say, the infrared spectrum) that the general public does not routinely occupy.

I'm thinking of this as something akin to one establishing a campsite in a wilderness area. Wouldn't one still have their 4th Amendment rights within the bounds of that campsite?
12.24.2005 4:00am
Paul Dietz (mail):
Some physics comments...

A terrorist might want to make a dirty bomb out of a material with high alpha or beta emission but low gamma emission (or, gamma emission at low enough energy that it is easily shielded with lead). Sr90, for example. These may require fairly sensitive detectors to locate, if shielded.

Secondly: all this talk about 'geiger counters' is a bit misleading. Geiger counters, while publically available and not very expensive, are also not very sensitive, particularly to gamma emissions. Scintillation detectors (which use large blocks of materials like sodium iodide, or a liquid such as naphthalene) or semiconductor detectors (large blocks of silicon or germanium, often operated at very low temperature) are far more sensitive, and also reveal the energy of the photons, from which one can deduce the composition of the emitter.

I suspect these more sophisticated sensors (and there are even more tricks that can be used, such as anticoincidence to remove cosmic ray background) would not be considered generally available, any more than a sophisticated IR sensor would be.

Gamma sensors *can* be made directional, for example by partially surrounding them with shielding, or using 'coded mask' techniques (a technique used in gamma ray telescopes in space).
12.24.2005 10:57am
PantsB (mail):
I'd like you compliment you on your foresight in this article and your statement:

"The measures we adopt today may thus be available to the government indefinitely. Imagine your least favorite president, from Nixon to Clinton, having powers like this in times of national turmoil. Police states can be built this way, and this isn't just hyperbole."

You could be this generations Madison.

However, I'm not sure why you reject the conclusion reason arrives at. If your gut and your head don't agree, doesn't the law fall on the side of your head?

"But by taking two measurements at different distances from a suspected source you can distinguish between the two. "
Except you may not be able to distinguish between a source that is not-entirely shielded and a non-shielded but weaker source.
12.24.2005 11:03am
Charlie (Colorado) (mail):

Except you may not be able to distinguish between a source that is not-entirely shielded and a non-shielded but weaker source.

No, that's not true --- since it's an inverse-square law, no matter what the intensity of the source is, you can distinguish between them because you can tell what the distance is.

Consider, eg, having two detectors one meter apart. If the emitter is 1 m away from the nearer detector on the line between the two, then the intensity at the more distant detector is 1/4 that of the nearer detector, a difference of 0.75. (1/1^2 vs 1/2^2). But if the source is 10 meters away, the difference is only 21/12100ths (1/10^2 - 1/11^2) or about 0.002.
12.24.2005 12:21pm
Just to add to the mix, note this article about a thyroid patient who has been stip searched twice by the NY transit police - apparently the subways also have rediation monitoring devices.
12.24.2005 12:38pm
Mary Katherine Day-Petrano (mail):
I am very curious, in light of this topic, how would one determine the curtilege of a live-aboard vessel at dock? Relative to a search on navigable waters.
12.24.2005 12:44pm
Adam S (mail) (www):
Paul, exfizz,

How portable and concealable are those more sophisticated detectors? Recall that this started because the President declared that undercover entry into certain sites didn't require a warrant.
12.24.2005 2:42pm
Paul Dietz (mail):
Sensitivity of a gamma ray detector is proportional to its mass, so anything small will be comparatively insensitive. Also, if the dimensions of the detector are less than the stopping distance of the compton-scattered electrons, the energy resolution will be poor. Semiconductor detectors with cryogenic cooling will be bulky and difficult to conceal.

From the reports I've read, the detector is mounted in a vehicle, and the 'undercover entry' means entering the parking lot.

BTW: there is a difference between a shielded strong source and an unshielded weak source. In the former case, most of the photons detected will have been scattered (but not absorbed) in the shielding, while in the latter case more will be unscattered. This will affect the energy spectrum in a noticable way. Scintillation and (even more so) semiconductor detectors tell you how much energy each photon deposits in the detector.
12.24.2005 6:37pm
Daniel Newby (mail) (www):
The photons received by a thermal imager are exactly the ones radiated by the building. It is no different than putting a crane over the building and measuring a zillion points on the building's surface by touching it with a thermometer. This is the technical basis for calling thermal imagery a search.

Ionizing radiation, however, interacts strongly with everything, including air. A photon is emitted from the source, totally absorbed by a molecule of air, and then a portion of the energy in the molecule is radiated as a brand-new photon. (The remainder of the energy remaining to do rude things to the molecule. It's called "ionizing" radiation for a reason.) So when a homeland security scanner finds radiation coming out of thin air, does that create reasonable suspicion of a potential public hazard in progress?

Regarding the "generally available" question, an electronics hobbyist can easily throw together a scintillator detector that works reasonably well. Unlike the thermal imagers that use fancy microbolometer arrays, scintillators are embarrassingly cheap and simple. A coincidence detector to distinguish cosmic rays from terrestrial emissions is also pretty straightforward.

It is not widely known, but small quantities of radionuclides can be possessed without needing a government license. They are readily available for calibrating and testing radiation detectors. (Think about it. If you use a Geiger counter for safety work, you have to know it isn't broken.) If a guy walks by on the sidewalk and the cops detect cobalt-60 rays coming from his briefcase, they do not have proof of a crime, just a suspicion based on an unusual observation.
12.25.2005 12:51am
Charlie (Colorado) (mail):

If a guy walks by on the sidewalk and the cops detect cobalt-60 rays coming from his briefcase, they do not have proof of a crime, just a suspicion based on an unusual observa

Well, yes and no. Since you can determine the distance from the difference in intensities between two separated detectors, you can backsolve that to figure out the source intensity. (I refuse to try to describe that in detail when I can't draw diagrams.) If you detect a couple of millicuries of 60C 4 feet away, you might not get too excited.
12.25.2005 2:07pm
Kevin L. Connors (mail) (www):
I believe, Mary Katherine, from Villamonte-Marquez, that it doesn't make a difference. Although that boat was anchored, not docked, the law seems pretty clear - authorities can board, visit "public areas" and inspect the documents of a vessel anywhere.
12.25.2005 4:45pm
exfizz (mail):
Adam S: "How portable and concealable are those more sophisticated detectors? Recall that this started because the President declared that undercover entry into certain sites didn't require a warrant."

Again, I'm out of practice, but simply googling "scintillation detector" gets you this $7,000 Amptek device, marketed explicitly for "Homeland Security applications." Not merely a counter, it does gamma/X-ray spectroscopy, i.e. it tells you which radionuclide you're dealing with. Sweet. Sew into a jacket an Amptek + GPS + small computer + custom software, and one walker can unobtrusively map a whole neighborhood in one day without taking his hands out of his pockets. You never even need to enter a building, you never "image" anything -- but you build up a few-meters-resolution map I(x,y) of radiation patterns. Do it day after day and you get I(x,y,t). That t term is nice to have, because dI/dt tells you a lot. Example:

JUDGE: You want a warrant to search a mosque?
PROSECUTOR: Your honor, the mosque is emitting gamma radiation.
DEFENSE: Ah, your honor, my client just remembered that his mosque is serving the spiritual needs of a cancer patient undergoing radiation therapy.
PROSECUTOR: Your honor, without entering or imaging the mosque we have triangulated the location of the alleged cancer patient. [pauses] He is in a broom closet and has not moved at all in four months. And this unfortunate individual tripled in size and started emitting thermal neutrons the night the a windowless van we've been surveilling parked at the mosque.
JUDGE: Here's your warrant.

(We physicists may tend to overthink the problem; but this time we don't have to outsmart Mother Nature, we just have to outsmart the other guy's lawyer.)

If we're talking about a mosque-sized building, simply being able to walk up to the front door, as opposed to pulling into the parking lot, could be a useful ability given that we're dealing with an r-2 law.

That's if you're looking for a fairly "hot" source. As Paul Dietz points out, if the source is shielded, you need a more massive detector. Fine, so you're driving around in an F250 with 1000kg of NaI in the back. If you're really serious, and if your @#$%&* lawyers allow you to do imaging, again you load Son Of This Guy into a moving van or chopper.
12.26.2005 12:20am
dennism (mail):
Isn't this the "obvious answer": the government can conduct the search, but if it's impermissible, it can't be used in Court.
12.26.2005 4:12pm
John Schulien:
Yes, Dennism. The appropriate counterquestion is, if the government is unable to convict the terrorist because of a lack of admissable evidence, is it obliged to return the nuclear weapon to the terrorist?
12.26.2005 5:26pm
Eirik (mail):
Hasn't the government been doing this since 9/11 in ports, anyway? I seem to recall a couple years back a freighter was refused entry into New York harbor because it was emitting a larger than normal amount of radiation. IIRC, it turned out to be some kind of floor tile that simple is a bit hotter than the background, but how is this different than driving down the street with a radiation detector?
12.26.2005 5:27pm
JackLifton (mail):
I realize that the United States of America is a Republic rather than a democracy with regard to the operations of of national government, and that we operate under a binding Federal Constitution. We should therefore legislate an exception to the "unreasonable" search and seizure provision of the Fourth Amendment of the US Constitution and let the US Supreme Court rule on it as soon as possible.

I propose a law that reads that the President and (law enforcement officers...) shall need no prior authorization, where they have reasonable belief that radioactive, bilological, or chemical materials are in the possession or under the control of those who intend to use them to harm others, to seek out, by any means technically reliable, said materials and take control over them. The possessors or owners of the material may be entitled to just compensation in the event that a court determines, after the seizure, that the (police) were mistaken in their belief of an unlawful intended use. In neither case will the materials be reurned to the original possessor without proof presented to the determining court of their lawful and safe use.
12.26.2005 5:40pm
Fede (mail):
What is their major objection to getting warrants?

What's yours for not getting warrants? Which is scarier: a government agency that puts a radiation detector in a van and occasionally cycles it through high-risk neighborhoods, or one which can easily get a warrant to search every house in an entire subdivision?
12.26.2005 6:18pm
Derek B Kite:
Law enforcement is fundamentally reactive. A crime is committed, then searches and evidence gathering is done in a way to convict. The tradeoff between public safety and rights tends towards rights, ie. I get shot before the police get involved. Society keeps functioning without me, the police and courts do their thing and possibly get whoever shot me off the streets for a while. Life goes on, at least for everyone else.

When there are stated threats, stated intentions to do harm, evidence of ability (9/11), how can the law enforcement model work? Society could cease to function, or be substantially impaired by some radiation bomb.

I don't know the answer, but I don't think that a strictly legalistic approach is adequate or appropriate.

And yes there is danger of overreach. As there is danger of underreach.

12.26.2005 9:35pm