April 19, 2014

Paul Ohm

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Do Judges Play a Role After the NSA Call Records Have Been Collected?

Those who defend the NSA’s massive call records collection program point out that although the program allows indiscriminate data collection, it also meaningfully restricts data analysis and use. They note, in particular, this paragraph from Director of National Intelligence Clapper’s June 6, 2013, press release:

By order of the FISC, the Government is prohibited from indiscriminately sifting through the telephony metadata acquired under the program. All information that is acquired under this program is subject to strict, court-imposed restrictions on review and handling. The court only allows the data to be queried when there is a reasonable suspicion, based on specific facts, that the particular basis for the query is associated with a foreign terrorist organization. Only specially cleared counterterrorism personnel specifically trained in the Court-approved procedures may even access the records.

It seems to me that some have probably misunderstood this paragraph to suggest that the judges of the FISA Court (FISC) play a role in approving each individual query made to the data, the way a judge approves a warrant to search for or seize evidence in a criminal case. An article in Slate explained, somewhat approvingly, that “the rules that most of us would apply at the collection stage—reasonable suspicion, specific facts, court approval—are applied instead at the query stage”. A blog post author on Forbes explained that “[i]n order to analyze the data at hand, the NSA must get a court order justified by the reasonable suspicion of an imminent terrorist act.” Some legal scholars may be making the same assumption.
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United States v. Jones is a Near-Optimal Result

This morning, the Supreme Court handed down its decision in United States v. Jones, the GPS tracking case, deciding unanimously that the government violated the defendant’s Fourth Amendment rights when it installed a wireless GPS tracking device on the undercarriage of his car and used it to monitor his movement’s around town for four weeks without a search warrant.

Despite the unanimous result, the court was not unified in its reasoning. Five Justices signed the majority opinion, authored by Justice Scalia, finding that the Fourth Amendment “at bottom . . . assure[s] preservation of that degree of privacy against government that existed when the Fourth Amendment was adopted” and thus analyzing the case under “common-law trespassory” principles.

Justice Alito wrote a concurring opinion, signed by Justices Ginsburg, Breyer, and Kagan, faulting the majority for “decid[ing] the case based on 18th-century tort law” and arguing instead that the case should be decided under Katz’s “reasonable expectations of privacy” test. Applying Katz, the four concurring Justices would have found that the government violated the Fourth Amendment because “long-term tracking” implicated a reasonable expectation of privacy and thus required a warrant.

Justice Sotomayor, who signed the majority opinion, wrote a separate concurring opinion, but more on that in a second.

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Supreme Court Takes Important GPS Tracking Case

This morning, the Supreme Court agreed to hear an appeal next term of United States v. Jones (formerly United States v. Maynard), a case in which the D.C. Circuit Court of Appeals suppressed evidence of a criminal defendant’s travels around town, which the police collected using a tracking device they attached to his car. For more background on the case, consult the original opinion and Orin Kerr’s previous discussions about the case.

No matter what the Court says or holds, this case will probably prove to be a landmark. Watch it closely.

(1) Even if the Court says nothing else, it will face the constitutionally of the use by police of tracking beepers to follow criminal suspects. In a pair of cases from the mid-1980′s, the Court held that the police did not need a warrant to use a tracking beeper to follow a car around on public, city streets (Knotts) but did need a warrant to follow a beeper that was moved indoors (Karo) because it “reveal[ed] a critical fact about the interior of the premises.” By direct application of these cases, the warrantless tracking in Jones seems constitutional, because it was restricted to movement on public, city streets.

Not so fast, said the D.C. Circuit. In Jones, the police tracked the vehicle 24 hours a day for four weeks. Citing the “mosaic theory often invoked by the Government in cases involving national security information,” the Court held that the whole can sometimes be more than the parts. Tracking a car continuously for a month is constitutionally different in kind not just degree from tracking a car along a single trip. This is a new approach to the Fourth Amendment, one arguably at odds with opinions from other Courts of Appeal.

(2) This case gives the Court the opportunity to speak generally about the Fourth Amendment and location privacy. Depending on what it says, it may provide hints for lower courts struggling with the government’s use of cell phone location information, for example.

(3) For support of its embrace of the mosaic theory, the D.C. Circuit cited a 1989 Supreme Court case, U.S. Department of Justice v. National Reporters Committee. In this case, which involved the Freedom of Information Act (FOIA) not the Fourth Amendment, the Court allowed the FBI to refuse to release compiled “rap sheets” about organized crime suspects, even though the rap sheets were compiled mostly from “public” information obtainable from courthouse records. In agreeing that the rap sheets nevertheless fell within a “personal privacy” exemption from FOIA, the Court embraced, for the first time, the idea that the whole may be worth more than the parts. The Court noted the difference “between scattered disclosure of the bits of information contained in a rap-sheet and revelation of the rap-sheet as a whole,” and found a “vast difference between the public records that might be found after a diligent search of courthouse files, county archives, and local police stations throughout the country and a computerized summary located in a single clearinghouse of information.” (FtT readers will see the parallels to the debates on this blog about PACER and RECAP.) In summary, it found that “practical obscurity” could amount to privacy.

Practical obscurity is an idea that hasn’t gotten much traction in the Courts since National Reporters Committee. But it is an idea well-loved by many privacy scholars, including myself, for whom it helps explain their concerns about the privacy implications of data aggregation and mining of supposedly “public” data.

The Court, of course, may choose a narrow route for affirming or reversing the D.C. Circuit. But if it instead speaks broadly or categorically about the viability of practical obscurity as a legal theory, this case might set a standard that we will be debating for years to come.

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If Wikileaks Scraped P2P Networks for "Leaks," Did it Break Federal Criminal Law?

On Bloomberg.com today, Michael Riley reports that some of the documents hosted at Wikileaks may not be “leaks” at all, at least not in the traditional sense of the word. Instead, according to a computer security firm called Tiversa, “computers in Sweden” have been searching the files shared on p2p networks like Limewire for sensitive and confidential information, and the firm supposedly has proof that some of the documents found in this way have ended up on the Wikileaks site. These charges are denied as “completely false in every regard” by Wikileaks lawyer Mark Stephens.

I have no idea whether these accusations are true, but I am interested to learn from the story that if they are true they might provide “an alternate path for prosecuting WikiLeaks,” most importantly because the reporter attributes this claim to me. Although I wasn’t misquoted in the article, I think what I said to the reporter is a few shades away from what he reported, so I wanted to clarify what I think about this.

In the interview and in the article, I focus only on the Computer Fraud and Abuse Act (“CFAA”), the primary federal law prohibiting computer hacking. The CFAA defines a number of federal crimes, most of which turn on whether an action on a computer or network was done “without authorization” or in a way that “exceeds authorized access.”

The question presented by the reporter to me (though not in these words) was: is it a violation of the CFAA to systematically crawl a p2p network like Limewire searching for and downloading files that might be mistakenly shared, like spreadsheets or word processing documents full of secrets?

I don’t think so. With everything I know about the text of this statute, the legislative history surrounding its enactment, and the cases that have interpreted it, this kind of searching and downloading won’t “exceed the authorized access” of the p2p network. This simply isn’t a crime under the CFAA.

But although I don’t think this is a viable theory, I can’t unequivocally dismiss it for a few reasons, all of which I tried to convey in the interview. First, some courts have interpreted “exceeds authorized access” broadly, especially in civil lawsuits arising under the CFAA. For example, back in 2001, one court declared it a CFAA violation to utilize a spider capable of collecting prices from a travel website by a competitor, if the defendant built the spider by taking advantage of “proprietary information” from a former employee of the plaintiff. (For much more on this, see this article by Orin Kerr.)

Second, it seems self-evident that these confidential files are being shared on accident. The users “leaking” these files are either misunderstanding or misconfiguring their p2p clients in ways that would horrify them, if only they knew the truth. While this doesn’t translate directly into “exceeds authorized access,” it might weigh heavily in court, especially if the government can show that a reasonable searcher/downloader would immediately and unambiguously understand that the files were shared on accident.

Third, let’s be realistic: there may be judges who are so troubled by what they see as the harm caused by Wikileaks that they might be willing to read the open-textured and mostly undefined terms of the CFAA broadly if it might help throw a hurdle in Wikileaks’ way. I’m not saying that judges will bend the law to the facts, but I think that with a law as vague as the CFAA, multiple interpretations are defensible.

But I restate my conclusion: I think a prosecution under the CFAA against someone for searching a p2p network should fail. The text and caselaw of the CFAA don’t support such a prosecution. Maybe it’s “not a slam dunk either way,” as I am quoted saying in the story, but for the lawyers defending against such a theory, it’s at worst an easy layup.

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Court Rules Email Protected by Fourth Amendment

Today, the United States Court of Appeals for the Sixth Circuit ruled that the contents of the messages in an email inbox hosted on a provider’s servers are protected by the Fourth Amendment, even though the messages are accessible to an email provider. As the court puts it, “[t]he government may not compel a commercial ISP to turn over the contents of a subscriber’s emails without first obtaining a warrant based on probable cause.”

This is a very big deal; it marks the first time a federal court of appeals has extended the Fourth Amendment to email with such care and detail. Orin Kerr calls the opinion, at least on his initial read, “quite persuasive” and “likely . . . influential,” and I agree, but I’d go further: this is the opinion privacy activists and many legal scholars, myself included, have been waiting and calling for, for more than a decade. It may someday be seen as a watershed moment in the extension of our Constitutional rights to the Internet.

And it may have a more immediate impact on Capitol Hill, because in its ruling the Sixth Circuit also declares part of the Stored Communications Act (SCA) of the Electronic Communications Privacy Act unconstitutional. 18 U.S.C. 2703(b) allows the government to obtain email messages with less than a search warrant. This section has been targeted for amendment by the Digital Due Process coalition of companies, privacy groups, and academics (I have signed on) for precisely the reason now attacked by this opinion, because it allows warrantless government access to communications stored online. I am sure some congressional staffers are paying close attention to this opinion, and I hope it helps clear the way for an amendment to the SCA, to fix a now-declared unconstitutional law, if not during the lame duck session, then early in the next Congressional term.

Update: Other reactions from Dissent and the EFF.

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A Good Day for Email Privacy: A Court Takes Back its Earlier, Bad Ruling in Rehberg v. Paulk

In March, the U.S. Court of Appeals for the Eleventh Circuit, the court that sets federal law for Alabama, Florida, and Georgia, ruled in an opinion in a case called Rehberg v. Paulk that people lacked a reasonable expectation of privacy in the content of email messages stored with an email provider. This meant that the police in those three states were free to ignore the Fourth Amendment when obtaining email messages from a provider. In this case, the plaintiff alleged that the District Attorney had used a sham subpoena to trick a provider to hand over the plaintiff’s email messages. The Court ruled that the DA was allowed to do this, consistent with the Constitution.

I am happy to report that today, the Court vacated the opinion and replaced it with a much more carefully reasoned, nuanced opinion.

Most importantly, the Eleventh Circuit no longer holds that “A person also loses a reasonable expectation of privacy in emails, at least after the email is sent to and received by a third party.” nor that “Rehberg’s voluntary delivery of emails to third parties constituted a voluntary relinquishment of the right to privacy in that information.” These bad statements of law have effectively been erased from the court reporters.

This is a great victory for Internet privacy, although it could have been even better. The Court no longer strips email messages of protection, but it didn’t go further and affirmatively hold that email users possess a Fourth Amendment right to privacy in email. Instead, the Court ruled that even if such a right exists, it wasn’t “clearly established,” at the time the District Attorney acted, which means the plaintiff can’t continue to pursue this claim.

I am personally invested in this case because I authored a brief asking the Court to reverse its earlier bad ruling. I am glad the Court agreed with us and thank all of the other law professors who signed the brief: Susan Brenner, Susan Freiwald, Stephen Henderson, Jennifer Lynch, Deirdre Mulligan, Joel Reidenberg, Jason Schultz, Chris Slobogin, and Dan Solove. Thanks also to my incredibly hard-working and talented research assistants, Nicole Freiss and Devin Looijien.

Updated: The EFF (which represents the plaintiff) is much more disappointed in the amended opinion than I. They make a lot of good points, but I prefer to see the glass half-full.

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The Gizmodo Warrant: Searching Journalists in the Terabyte Age

Last Friday night, police officers in California used a warrant to search the home of Jason Chen, the Gizmodo blogger who wrote about the iPhone prototype found in a Redwood City bar. Orin Kerr has written an interesting post assessing the legality of the search. I wanted to touch on an important issue he didn’t discuss: Whether the search the police are conducting is unconstitutionally overbroad.

Orin discusses two laws that specifically shield journalists from being the target of a search, the California Reporter’s Shield Law, found jointly at California Penal Code 1524(g) and California Evidence Code 1070, and the federal Privacy Protection Act (PPA), 42 U.S.C. 2000aa. Both laws were written to limit the impact of Zurcher v. Stanford Daily, a U.S. Supreme Court case authorizing the use of a warrant to search a newspaper’s offices. The Supreme Court decided Zurcher in 1978, and Congress enacted the PPA in 1980 (and amended it in unrelated ways in 1996). I’m not sure when the California law was enacted, but I bet it’s of similar vintage. In other words, all of the rules that govern police searches of news offices were created in the age of typewriters, desks, filing cabinets, and stacks of paper.

Now, flash forward thirty years. The police who searched Jason Chen’s home seized the following: A macbook, HP server, two Dell desktop computers, iPad, ThinkPad, two MacBook Pros, IOmega NAS, three external hard drives, and three flash drives. They also seized other storage-containing devices, including two digital cameras and two smart phones. If Jason Chen’s computing habits are anything like mine, the police likely seized many terabytes of disk space, storing hundreds of thousands (millions?) of files, containing information stretching back years. And they took all of this information to investigate an alleged crime (the sale of the iPhone prototype) that could not have happened more than 37 days before the search (the iPhone was found on March 18th), which they learned about from a blog post published four days before the search.

I’m deeply concerned about overbreadth as the police begin to search through these terabytes of information. The police now possess, intermingled with the evidence of the alleged crime they are investigating, hundreds of thousands of documents belonging to a journalist/blogger that are utterly irrelevant to their investigation. Jason Chen has been blogging for Gizmodo since 2006, and he’s probably written hundreds of stories. The police likely have thousands of email messages revealing confidential sources, detailing meetings, and trading comments with editors, and thousands of other documents bearing notes from interviews, drafts of articles, and other sensitive information. Because of Chen’s beat, some of these documents probably reveal secrets of great economic and business value in the Silicon Valley. Under traditional, outmoded Fourth Amendment rules, the police can read every single document they possess, so long as they intend only to look for evidence of the crime, and under the “plain view rule,” they can use any evidence they find of other, unrelated crimes in court against Chen or anyone else.

If the California state courts share my concerns about overbreadth, they should consider embracing the very sensible rules for search warrants for computer hard drives (in any case, not just those involving journalists) adopted last year by the Ninth Circuit in United States v. Comprehensive Drug Testing. To paraphrase, in cases involving the search and seizure of computers, the Ninth Circuit requires five things: (1) the government must waive the plain view rule, meaning they must agree not to use evidence of crimes other than the one under investigation that led to the warrant; (2) the government must wall off the forensic experts who search the hard drive from the investigating the case; (3) the government must explain the “actual risks of destruction of information” they would face if they weren’t allowed to seize entire computers; (4) the government must use a search protocol to designate what information they can give to the investigating agents; and (5) the government must destroy or return non-responsive data.

These rules are especially needed when the target of a police search is a journalist (in fact, they may not go far enough). And these rules may be required under Zurcher. In justifying the search of the newspaper’s offices in Zurcher, the Supreme Court agreed that when the Fourth Amendment’s search and seizure rules collide with First Amendment values, like freedom of the press, the “Fourth Amendment must be applied with ‘scrupulous exactitude.’” The court went on to explain why ordinary search warrants for news offices (remember, back in the age of paper files) meet this heightened standard:

There is no reason to believe, for example, that magistrates cannot guard against searches of the type, scope, and intrusiveness that would actually interfere with the timely publication of a newspaper. Nor, if the requirements of specificity and reasonableness are properly applied, policed, and observed, will there be any occasion or opportunity for officers to rummage at large in newspaper files or to intrude into or to deter normal editorial and publication decisions.

When the California state courts combine this thirty-year-old statement of the law with the modern realities of terabyte storage devices, they should hold that the Fourth Amendment requires magistrate judges to play an integral and active role in the administration of the search of Jason Chen’s computers and other storage devices. At the very least, the courts should forbid the police from looking at any file timestamped before March 18, 2010, and in addition, they should force the police to comply with the Comprehensive Drug Testing rules. In the terabyte age, these rules are necessary at a minimum to prevent the police from interfering with a free press.

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Netflix Cancels the Netflix Prize 2

Today, Netflix announced it is canceling its plans for a second Netflix Prize contest, one that reportedly would have involved the release of more information than the first. As I argued earlier, I feared that the new contest would have put the supposedly private movie viewing and rating habits of Netflix customers at great risk, and I applaud Netflix for making a very responsible decision. No doubt, pressure from the private lawsuit and FTC investigation helped Netflix make up its mind, and both are reportedly going away as a result of today’s action.

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Netflix's Impending (But Still Avoidable) Multi-Million Dollar Privacy Blunder

In my last post, I had promised to say more about my article on the limits of anonymization and the power of reidentification. Although I haven’t said anything for a few weeks, others have, and I especially appreciate posts by Susannah Fox, Seth Schoen, and Nate Anderson. Not only have these people summarized my article well, they have also added a lot of insightful commentary, and I commend these three posts to you.

Today brings news relating to one of the central examples in my paper: Netflix has announced plans to commit a privacy blunder that could cost it millions of dollars in fines and civil damages.

In my article, I focus on Netflix’s 2006 decision to release millions of records containing the movie rating preferences of “anonymized” users to the public, in order to fuel a crowd-sourcing competition called the Netflix Prize. The Netflix Prize has been a huge win for Netflix’s public relations, but it has also been a win for academics, who have used the data to improve the science of guessing human behavior from past preferences.

The Netflix Prize was also a watershed event for reidentification research because Arvind Narayanan and Vitaly Shmatikov of U. Texas revealed that they could reidentify some of the “anonymized” users with ease, proving that we are more uniquely tied to our movie rating preferences than intuition would suggest. In my paper, I argue that we should worry about this privacy breach even if we don’t think movie ratings are terribly sensitive, because it can be used to enable other, more terrifying privacy breaches.

I never argue, however, that Netflix deserves punishment or sanction for having released this data. In my opinion, Netflix acted pretty responsibly. It consulted with computer scientists in a (failed) attempt to anonymize successfully. It tried perturbing the data in order to make reidentification harder. And other experts seem to have been surprised by how easy it was for Narayanan and Shmatikov to reidentify. Even with the benefit of hindsight, I find nothing to blame in how Netflix handled the privacy implications of what it did.

Although I give Netflix a pass for its past privacy breach, I am astonished to learn from the New York Times that the company plans a second act:

The new contest is going to present the contestants with demographic and behavioral data, and they will be asked to model individuals’ “taste profiles,” the company said. The data set of more than 100 million entries will include information about renters’ ages, gender, ZIP codes, genre ratings and previously chosen movies. Unlike the first challenge, the contest will have no specific accuracy target. Instead, $500,000 will be awarded to the team in the lead after six months, and $500,000 to the leader after 18 months.

Netflix should cancel this new, irresponsible contest, which it has dubbed Netflix Prize 2. Researchers have known for more than a decade that gender plus ZIP code plus birthdate uniquely identifies a significant percentage of Americans (87% according to Latanya Sweeney’s famous study.) True, Netflix plans to release age not birthdate, but simple arithmetic shows that for many people in the country, gender plus ZIP code plus age will narrow their private movie preferences down to at most a few hundred people. Netflix needs to understand the concept of “information entropy”: even if it is not revealing information tied to a single person, it is revealing information tied to so few that we should consider this a privacy breach.

I have no doubt that researchers will be able to use the techniques of Narayanan and Shmatikov, together with databases revealing sex, zip code, and age, to tie many people directly to these supposedly anonymized new records.

Because of this, if it releases the data, Netflix might be breaking the law. The Video Privacy Protection Act (VPPA), 18 USC 2710 prohibits a “video tape service provider” (a broadly defined term) from revealing “personally identifiable information” about its customers. Aggrieved customers can sue providers under the VPPA and courts can order “not less than $2500″ in damages for each violation. If somebody brings a class action lawsuit under this statute, Netflix might face millions of dollars in damages.

Additionally, the FTC might also decide to fine Netflix for violating its privacy policy as an unfair business practice.

Either a lawsuit under the VPPA or an FTC investigation would turn, in large part, on one sentence in Netflix’s privacy policy: “We may also disclose and otherwise use, on an anonymous basis, movie ratings, consumption habits, commentary, reviews and other non-personal information about customers.” If sued or investigated, Netflix will surely argue that its acts are immunized by the policy, because the data is disclosed “on an anonymous basis.” While this argument might have carried the day in 2006, before Narayanan and Shmatikov conducted their study, the argument is much weaker in 2009, now that Netflix has many reasons to know better, including in part, my paper and the publicity surrounding it. A weak argument is made even weaker if Netflix includes the kind of data–ZIP code, age, and gender–that we have known for over a decade fails to anonymize.

The good news is Netflix has time to avoid this multi-million dollar privacy blunder. As far as I can tell, the Netflix Prize 2 has not yet been launched.

Dear Netflix executives: Don’t do this to your customers, and don’t do this to your shareholders. Cancel the Netflix Prize 2, while you still have the chance.

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Anonymization FAIL! Privacy Law FAIL!

I have uploaded my latest draft article entitled, Broken Promises of Privacy: Responding to the Surprising Failure of Anonymization to SSRN (look carefully for the download button, just above the title; it’s a little buried). According to my abstract:

Computer scientists have recently undermined our faith in the privacy-protecting power of anonymization, the name for techniques for protecting the privacy of individuals in large databases by deleting information like names and social security numbers. These scientists have demonstrated they can often “reidentify” or “deanonymize” individuals hidden in anonymized data with astonishing ease. By understanding this research, we will realize we have made a mistake, labored beneath a fundamental misunderstanding, which has assured us much less privacy than we have assumed. This mistake pervades nearly every information privacy law, regulation, and debate, yet regulators and legal scholars have paid it scant attention. We must respond to the surprising failure of anonymization, and this Article provides the tools to do so.

I have labored over this article for a long time, and I am very happy to finally share it publicly. Over the next week, or so, I will write a few blog posts here, summarizing the article’s high points and perhaps expanding on what I couldn’t get to in a mere 28,000 words.

Thanks to Ed, David, and everybody else at Princeton’s CITP for helping me develop this article during my visit earlier this year.

Please let me know what you think, either in these comments or by .