When a U.S. citizen returns home from abroad, the federal government asserts a hugely intrusive prerogative: the option to search not only their person and luggage, but the entire contents of their mobile phone, tablet, or laptop––sans a warrant, probable cause, or reasonable suspicion––as if the Fourth Amendment is null at the border.

Two U.S. Senators, Republican Rand Paul and Democrat Ron Wyden, are outraged by those intrusions, and hope to end them with a new bill they’ve put forward. In the House, Blake Farenthold of Texas and Jared Polis of Colorado are their analogs.

The strangeness of the status quo is easiest to understand if one first reflects on what the Fourth Amendment demands of cell phone searches conducted anywhere but a point of entry. Chief Justice John Roberts published the controlling opinion on that matter after hearing the case of David Riley at the Supreme Court. Riley was stopped for driving with expired tags in the state of California. A police officer quickly learned that he was driving on a suspended license. While taking an inventory of the car prior to having it towed to an impound lot, two loaded handguns were found hidden under the hood. Other items in the car suggested that the motorist was associated with the Bloods street gang.

In the course of arresting Riley, police officers confiscated and searched his cell phone. On it they found evidence suggesting his involvement in a drive-by shooting.

Mr. Riley was charged with attempted murder.

Despite all that, the Supreme Court ruled that the police violated Riley’s Fourth Amendment rights by searching the cell phone in his pocket upon his arrest. Evidence of attempted murder was excluded for lack of a proper search warrant.

Why was a warrant needed, given that police officers are perfectly entitled to examine most physical objects that are found on an individual being lawfully arrested?

Roberts reasoned that unlike most physical objects, the digital contents of a cell phone neither threaten the physical safety of police nor risk aiding arrestees in an escape nor threaten the preservation of evidence. The state has a much lesser interest in conducting an immediate search. And when balancing state interests against the individual’s interest in privacy, cell phones are different in that they “place vast quantities of personal information literally in the hands of individuals.”

Roberts spent a lot of time emphasizing that final point.

“Before cell  phones, a search of a person was limited by physical realities and tended as a general matter to constitute only a  narrow  intrusion  on  privacy. Most people cannot lug around every piece of mail they have received for the past several months,  every  picture  they  have  taken,  or  every  book  or article they have read—nor would they have any reason to attempt to do so,” Roberts explained. “Now the person who is not carrying a cell phone,  with all it contains,  is the exception.”

He acknowledged his ruling would impose a burden on police:

We  cannot deny that our decision today will have  an  impact on the ability of law enforcement to combat crime. Cell  phones have become  important tools in facilitating coordination and communication among members of criminal  enterprises, and can  provide valuable  incriminating  information about dangerous criminals.  

But he reasoned that even a person’s home, where Americans traditionally enjoyed the highest degree of Fourth Amendment protection, might contain but a fraction of the private details a cell phone would––and that protecting privacy has costs.

“Cell phones are not just another convenience,” Roberts wrote. “With all  they contain and all they may reveal, they hold for many Americans  ‘the  privacies of life.’ That  technology now allows an individual to carry such information in his hand does not make the information any less worthy of  the protection for which the Founders fought. Our answer to the question of what police must do before searching a cell phone seized incident to an arrest is accordingly simple— get a warrant.”

Ever since, a warrant has been required to search the cell phones of people who are being arrested, even for the most serious crimes. And that standard raises a question:

If a constitutional balancing of state interests and individual privacy requires police officers to obtain a warrant to search a cell phone to meet Fourth Amendment muster, even when the device belongs to a criminal who has just perpetrated a heinous crime, what kind of sense does it make to simultaneously allow the government to conduct warrantless searches on the electronic devices of innocent American travelers, at the whim of a bureaucrat, merely for coming home?

That’s precisely what the Ninth Circuit Court of Appeals allowed in the 2008 case United States v. Arnold. The case concerned Michael Arnold, a 43-year-old American citizen who flew from the Philippines to Los Angeles, where he proceeded to customs.

Officer Laura Peng asked him to turn on his laptop computer to see if it was working. Its desktop displayed numerous icons, including one entitled “Kodak Pictures” and another entitled “Kodak Memories.” Agents clicked on the Kodak folders, opened the image files, and viewed the photos, “including one that depicted two nude women.” Supervisors were called, and an ensuing search of the computer unearthed “numerous images depicting what they believed to be child pornography.”

At trial, the defendant tried to suppress those files. As the appeals court later summarized:

Arnold argues that the district court was correct in concluding that reasonable suspicion was required to search his laptop at the border because it is distinguishable from other containers of documents based on its ability to store greater amounts of information and its unique role in modern life. Arnold argues that “laptop computers are fundamentally different from traditional closed containers,” and analogizes them to “homes” and the “human mind.” Arnold’s analogy of a laptop to a home is based on his conclusion that a laptop’s capacity allows for the storage of personal documents in an amount equivalent to that stored in one’s home. He argues that a laptop is like the “human mind” because of its ability to record ideas, e-mail, internet chats and web-surfing habits.

Arnold’s arguments sound a lot like what Roberts would endorse a half-dozen years later. But the Ninth Circuit judges rejected Arnold’s argument, reasoning in part that “Arnold has failed to distinguish how the search of his laptop and its electronic contents is logically any different from the suspicionless border searches of travelers’ luggage that the Supreme Court and we have allowed,” and that “Arnold’s analogy to a search of a home based on a laptop’s storage capacity is without merit.” What’s more, the court ruled that “case law does not support a finding that a search which occurs in an otherwise ordinary manner, is ‘particularly offensive’ simply due to the storage capacity of the object being searched.” (If the content of our brains could be scanned would customs officials be entitled to search and store an unabridged copy and call it “otherwise ordinary”?)

Given Robert’s opinion in the Riley case and Justice Sonia Sotomayor’s “mosaic theory,” which judges the intrusiveness of a search by looking at the totality of information that can be pieced together through the relevant technology, appeals court precedents on device searches at borders seem ripe for reversal.

Senators Paul and Wyden are moving to safeguard Fourth Amendment rights without waiting for the high court (or risking a ruling in the other direction).

“The privacy interest of United States persons in the digital contents of their electronic equipment, the digital contents of their online accounts, and the nature of their online presence differs in both degree and kind from their privacy interest in closed containers,” their bill asserts. “Accessing the digital contents of electronic equipment, accessing the digital contents of an online account, or obtaining information regarding the nature of the online presence of a United States person entering or exiting the United States, without a lawful warrant based on probable cause, is unreasonable under the Fourth Amendment to the Constitution.”

Reuters reports that “the bill would also bar officials from delaying or denying entry into the United States if a person refused to share passwords, personal information numbers, social media or online account information or access credentials.” Imagine having to share access to every email you’ve ever written, or the password to your online banking app, or sensitive trade secrets, to reenter your country!

As Roberts once put it:

Although the data stored on a cell phone is distinguished from physical records by quantity alone, certain types of data are also qualitatively different. An Internet search and browsing history... could reveal an individual’s private interests or concerns—perhaps a search for certain symptoms of disease, coupled with frequent visits to WebMD. Data on a cell phone can also reveal where a person has been. Historic location information is a standard feature on many smart phones and can reconstruct someone’s specific movements down to the minute, not only around town but also within a particular building.

Mobile application software on a cell phone, or “apps,”offer a range of tools for managing detailed information about all aspects of a person’s life. There are apps for Democratic Party news and Republican Party news; apps for alcohol, drug, and gambling addictions; apps for sharing prayer requests; apps for tracking pregnancy symptoms; apps for planning your budget; apps for every conceivable hobby or pastime; apps for improving your romantic life. There are popular apps for buying or selling just about anything, and the records of such transactions may be accessible on the phone indefinitely.

To allow agents of the state to access all that on a whim, to ogle honeymoon photos, probe political beliefs, peruse texts, and more, makes a mockery of the Fourth Amendment and limited government, and does precious little to make Americans safer. An effort at restoring the Constitution at the customs kiosk is long overdue.