[UPDATE: Analysis, and, in some measure the bottom line, substantially revised.] The Sacramento Bee reports:
The California Department of Fish and Game will stage three roadside checkpoints in Placer County on Sunday in an effort to catch hunting violations....
"The checkpoint is there to find violations of the Fish and Game Code," said Placer County Game Warden Brian Moore. "It could be anything — out of season hunting or animals that are fully protected — that could come through." ...
Wardens will stop vehicles to inquire about hunting and fishing activity and check licenses.
That's pretty clearly a Fourth Amendment violation, under the Supreme Court's decision in City of Indianapolis v. Edmond (2000), which held that similar checkpoints aimed at uncovering drug couriers were unconstitutional. Here's a relevant excerpt from Edmond:
The Fourth Amendment requires that searches and seizures be reasonable. A search or seizure is ordinarily unreasonable in the absence of individualized suspicion of wrongdoing. Chandler v. Miller, 520 U.S. 305, 308 (1997). While such suspicion is not an "irreducible" component of reasonableness, we have recognized only limited circumstances in which the usual rule does not apply.
For example, we have upheld certain regimes of suspicionless searches where the program was designed to serve "special needs, beyond the normal need for law enforcement." ... We have also upheld brief, suspicionless seizures of motorists ... at a sobriety checkpoint aimed at removing drunk drivers from the road, Michigan Dept. of State Police v. Sitz, 496 U.S. 444 (1990). In addition, in Delaware v. Prouse, 440 U.S. 648, 663 (1979), we suggested that a similar type of roadblock with the purpose of verifying drivers' licenses and vehicle registrations would be permissible. In none of these cases, however, did we indicate approval of a checkpoint program whose primary purpose was to detect evidence of ordinary criminal wrongdoing....
In Sitz, we evaluated the constitutionality of a Michigan highway sobriety checkpoint program. The Sitz checkpoint involved brief suspicionless stops of motorists so that police officers could detect signs of intoxication and remove impaired drivers from the road. Motorists who exhibited signs of intoxication were diverted for a license and registration check and, if warranted, further sobriety tests. This checkpoint program was clearly aimed at reducing the immediate hazard posed by the presence of drunk drivers on the highways, and there was an obvious connection between the imperative of highway safety and the law enforcement practice at issue. The gravity of the drunk driving problem and the magnitude of the State's interest in getting drunk drivers off the road weighed heavily in our determination that the program was constitutional....
We further indicated in Prouse that we considered the purposes of ... a hypothetical [license and registration verification] roadblock to be distinct from a general purpose of investigating crime. The State proffered the additional interests of "the apprehension of stolen motor vehicles and of drivers under the influence of alcohol or narcotics" in its effort to justify the discretionary spot check. We attributed the entirety of the latter interest to the State's interest in roadway safety. We also noted that the interest in apprehending stolen vehicles may be partly subsumed by the interest in roadway safety. We observed, however, that "[t]he remaining governmental interest in controlling automobile thefts is not distinguishable from the general interest in crime control." Not only does the common thread of highway safety thus run through Sitz and Prouse, but Prouse itself reveals a difference in the Fourth Amendment significance of highway safety interests and the general interest in crime control....
So highway checkpoints aimed at interdicting threats to highway traffic themselves are generally constitutional (which may also help explain airport searches). But suspicionless highway checkpoints aimed at catching people who commit other crimes, whether drug trafficking or illegal hunting, are generally not constitutional (unless some other exception kicks in, and none of those would apply here).
UPDATE: But while that is still my view of the best reading of Edmond, Orin pointed out to me that other cases have generally upheld hunting checkpoints. Some of these (State v. Sherburne, 571 A.2d 1181 (Me. 1990), and People v. Layton, 552 N.E.2d 1280 (Ill. App. Ct. 1990)) are pre-Edmond, and strike me as inconsistent with Edmond's reasoning. But the Ninth Circuit's decision last month in United States v. Fraire likewise upheld a hunting checkpoint at the entrance to a national park:
We first address whether the checkpoint was unconstitutional as a general crime control device. In Edmond, the city of Indianapolis operated vehicle checkpoints on city streets in an effort to discover and interdict illegal drugs. The Court held that the checkpoint program violated the Fourth Amendment because the "primary purpose" was to "uncover evidence of ordinary criminal wrongdoing." The Court distinguished two prior cases permitting checkpoints, Martinez-Fuerte and Sitz, on the grounds that the checkpoints in those cases served purposes other than ordinary crime control. In Martinez-Fuerte, the Court upheld the constitutionality of an immigration checkpoint near the U.S.-Mexico border. In Sitz, the Court upheld the constitutionality of a sobriety checkpoint that examined all drivers passing through for signs of intoxication. In Edmond, the Court explained why the primary purpose of the checkpoints in Martinez-Fuerte and Sitz were not the detection of ordinary criminal wrongdoing. The Court acknowledged that "[s]ecuring the border and apprehending drunk drivers are, of course, law enforcement activities, and law enforcement officers employ arrests and criminal prosecutions in pursuit of these goals." However, the checkpoint program in Sitz "was clearly aimed at reducing the immediate hazard posed by the presence of drunk drivers on the highways, and there was an obvious connection between the imperative of highway safety and the law enforcement practice at issue." As for Martinez-Fuerte, the objective there was to "intercept illegal aliens" and "to serve purposes closely related to the problems of policing the border[.]"
We must now determine whether the checkpoint in this case is a general crime control device, as in Edmond, or whether it serves a different purpose, as in Sitz or Martinez- Fuerte. The district court found that the checkpoint's purposes included "catching violators, ... deterrence, education and in turn wildlife protection." This finding is supported by Ranger Schifsky's testimony at the evidentiary hearing, who testified that the checkpoint was aimed at mitigating the effects of the illegal taking of animals in the park. That the checkpoint accomplished this goal through the use of law enforcement techniques does not automatically transform it into a crime control device for Fourth Amendment purposes.
The checkpoint in this case is analogous to the checkpoint upheld in Sitz and is distinguishable from the checkpoint in Edmond. A critical factor in Sitz was the close connection between the checkpoint and the harm it was seeking to prevent. Sitz (describing the "obvious connection between the imperative of highway safety and the law enforcement practice at issue" in Sitz); id. (emphasizing the "close connection to roadway safety"). Likewise, here, the checkpoint was situated at an entrance to the park and sought to counter illegal hunting within that park. Unlike the drug crimes addressed by the Edmond checkpoint, which occur throughout the nation, the wildlife offenses here are specific to national parks. Further, just as the Sitz checkpoint prevented an immediate harm to motorists, the checkpoint here prevents hunters from destroying a precious natural resource. It does so by catching poachers before they can kill additional animals, by deterring would-be poachers, and by educating the park-going public about the hunting prohibition. The goal was prevention, not arrests.
I confess that I do not find this argument persuasive, even taking into account Martinez-Fuerte (which Edmond treated as being closely linked to the special "border context"). Among other things, the goal of much criminal law is "prevention" via "deterr[ence]" and not just "arrests" when deterrence fails; and one could equally well say that the checkpoint in Edmond was aimed at preventing the "destr[uction of] a precious natural resource," which is to say the health of Americans.
At the same time, this might just reflect how unclear the administrative search/law enforcement search line is; perhaps there is no crisp line to be drawn here, and the Ninth Circuit's and California's position is as well-founded -- or as ill-founded -- as mine. And certainly in light of the Ninth Circuit decision, California is entitled to treat the checkpoint as constitutional, at least if it is "situated at an entrance to the park," as opposed to far enough away from the entrance (query how relevant this should be, but the Ninth Circuit seems to suggest that it is relevant enough to be worth mentioning).
Thanks to Gregory Broderick for the pointer, and to Orin for pointing me to the lower court caselaw on this.