The good news is the Supreme Court's Riley decision forces law enforcement to obtain warrants before searching cell phones. The bad news, apparently, is everything else. To begin with, particularity remains a problem. As the Supreme Court pointed out in its decision, people's entire lives are contained in their cell phones. When searching for what's relevant to the suspected criminal activity, the government is pretty much free to dig through these "lives" to uncover what it needs to move forward with prosecution.
The lack of strict parameters (perhaps an impossibility given the nature of digital communications/data) leads to fishing expeditions operating under the cover of Fourth Amendment adherence. There's no way to prevent trolling for evidence of unrelated criminal activity. The only recourse is to challenge it after it happens. Sometimes the courts find the government has gone too far. Other times, courts say the evidence would have been "inevitably discovered" in the course of the search and prevent it from being suppressed.
Then there are decisions like the one reached by a federal court in South Dakota -- one that says just because one law enforcement agency deployed a warrant to image the contents of a cell phone doesn't mean other law enforcement agencies can take a look at it without obtaining a warrant of their own.
Volokh Conspiracy's Orin Kerr snagged the decision and added some brief analysis. A cell phone seized by local police was also apparently of interest to the federal Bureau of Alcohol, Tobacco and Firearms (ATF), which was running its own investigation on the same subject. The local cops were looking for counterfeiting evidence, while the ATF was interested in firearms-related evidence.
The locals obtained a warrant and imaged the phone's contents. In the course of its investigation, the ATF pulled up the suspect's file and noticed the recent arrest and seizure of the suspect's cell phone. The Huron (SD) police department helpfully informed the ATF that it had a copy of the cell phone's contents that the ATF could take a look at. The ATF accepted the offer, but did not perform the crucial step of obtaining a warrant. That misstep cost the ATF its evidence.
According to the government, all evidence seized -- even if unrelated to the investigation at hand -- should be accessible to any law enforcement agency without obtaining another warrant. Because teamwork. The court disagrees [PDF], pointing out that the government's asking the court to grant it an open-ended fishing license for all electronic devices seized with a warrant:
The government argues that this conclusion is “impractical and is contrary to the nature of police investigations and collaborative law enforcement among different agencies.” The government’s position, however, overlooks the ultimate touchstone of the Fourth Amendment: reasonableness. Riley, 134 S. Ct. at 2482.
According to the government, law enforcement agencies can permanently save all unresponsive data collected from a cell phone after a search for future prosecutions on unrelated charges. If the government’s argument is taken to its natural conclusion, then this opens the door to pretextual searches of a person’s cell phone for evidence of other crimes. Under the government’s view, law enforcement officers could get a warrant to search an individual’s cell phone for minor infractions and then use the data to prosecute felony crimes. No limit would be placed on the government’s use or retention of unresponsive cell phone data collected under a valid warrant.
The court also disagrees with the government's plain view defense. In order for the "plain view" exception to work, there has to be justification for the "view" itself. In this case, the ATF had no justification for viewing the contents of a cell phone seized by another agency for an unrelated investigation.
The government also argued that the exclusionary rule shouldn't be applied to the evidence it obtained without a warrant. The court again disagrees, pointing out that the government will suffer minimally from the exclusion of evidence it apparently wasn't planning to introduce anyway. In addition, a failure to enforce the exclusionary rule in cases like these would just result in more governmental fishing trips.
Here, the cost of applying the exclusionary rule is minimized because the evidence is peripheral in nature and not directly related to the firearms offense. The government’s actions also suggest the evidence is not necessary for a conviction. Prior to Agent Fair’s search of the iPhone data, the government was ready to proceed with trial on January 3, 2017. Minutes before voir dire, the parties addressed a late discovery issue, and the court granted a continuance. If the issue had not come before the court, the government would have tried its case, and the iPhone data would not have been used.
In contrast, the benefits of applying the exclusionary rule in this case are clear. If the exclusionary rule is not applied, law enforcement agencies will have carte blanche authority to obtain a warrant for all data on a cell phone, keep the unresponsive data forever, and then later use the data for criminal prosecutions on unrelated charges—erasing the protections specifically contemplated in Riley.
All well and good as far as it goes for upholding Fourth Amendment protections, but as Orin Kerr points out, the court seems to be balancing the government's losses against the plaintiff's rights before arriving at this conclusion.
As I have written before, I don’t think it works to do this kind of case-by-case cost/benefit balancing when applying exclusionary rule precedents. But if the evidence isn’t important, the government isn’t going to file an appeal of the decision granting the motion to suppress. This decision is likely the end of the road in terms of judicial review of the Fourth Amendment issue.
They don't call the exclusionary rule a RULE for no reason. When rights are violated, exclusion is the proper remedy. Whether or not it damages the government's prosecution should be a distant secondary concern.