An engineer from NASA's Jet Propulsion Laboratory. A Wall Street Journal reporter and a French-American photojournalist. An independent filmmaker. An electronics salesman.

These are some of the many American citizens re-entering the country who have been subjected to searches of their cellphones and questioning about their social media.

Such invasions of travelers' private communications are extremely intrusive and have been conducted even when officials don't apparently have reason to think the person has done something wrong. And the government has lately increased the practice dramatically — even though recent legal decisions raise serious questions about its constitutionality.

Because people keep ever more of their personal details on their phones and computers, it is particularly egregious that the government should claim some right to unfettered access to these devices simply because a person travels abroad.

On Monday, the Knight First Amendment Institute at Columbia University — whose mission is to defend free speech in the digital age — filed a lawsuit seeking to compel the government to release information on the number of travelers whose devices have been searched, the policies related to searching cellphones containing sensitive and confidential information, and the findings of internal audits about the device search program.

Border searches of electronic devices by the Department of Homeland Security have risen exponentially in recent years, from about 5,000 device searches in 2015 to about 25,000 in 2016, according to press reports that cited DHS data. During the Trump administration, the intrusions appear to have become even more frequent; in February 2017 alone, border officials searched 5,000 devices.

And why is this happening? A U.S. Customs and Border Protection policy since 2009 authorizes officers to seize and search a traveler's electronic devices even if the person is not suspicious. The policy was always legally dubious, but it has become indefensible in light of the Supreme Court's 2014 landmark decision in Riley v. California.

The court held that police generally can't seize a person's cellphone as part of an arrest without first obtaining a warrant that is backed by evidence that the cellphone contains evidence of a crime and is signed by a judge.

A cellphone contains "the sum of an individual's private life," Chief Justice John Roberts wrote for the court. The search of a smartphone is nothing like the search of a duffle bag. What people store on their cellphones -- including Internet browsing history, medical records, family photos, GPS location data, financial information, and apps related to dating, addiction and hobbies -- is vastly more sensitive than what people used to carry in their pockets, backpacks, or purses, or even keep in their homes.

Searches of electronic devices when there is no basis for suspicion to search them raise serious concerns relating to the freedoms of speech and association. As Justice Sonia Sotomayor observed in another recent Supreme Court case, "[a]wareness that the government may be watching chills associational and expressive freedoms." Americans will be justifiably concerned about speaking freely if, simply because they travel internationally, the government is given unlimited authority to read through their emails, texts, social media posts and the like.

The implications may be especially significant for a free press. Suspicionless searches of cellphones threaten the ability of journalists and their sources to report on important international issues, which deprives the public of its right to know about those issues.

Numerous reports show that journalists, lawyers and activists — particularly those who cover civil wars and terrorism or travel to conflict areas — have had their cellphones and devices searched at the U.S. border, where officers have demanded their passwords and read their communications with sources.

Those sources will likely be leery of sharing information with journalists and activists if their identities and reports may be revealed to the U.S. government at the border.

Anecdotal evidence about how the government is using its authority to conduct suspicionless electronic device searches is disturbing but incomplete. The public has a right to see a fuller picture, as many civil liberties groups have asked the government to provide.

Our freedom of information lawsuit request seeks a range of information, but one of the items we seek may be especially revealing: We've asked for the database of the Treasury Enforcement Communications System that houses information about every device-search at the border, including the reason for the search, the country of origin of the traveler, and the traveler's race and ethnicity.

The government created this database in response to concerns voiced by the Department of Homeland Security's civil rights office several years ago about the possibility that searches might be conducted in a discriminatory or otherwise unlawful way.

Disclosure of the database — perhaps with narrow redactions to protect legitimate national security and privacy interests — would help the public understand the answer to basic questions about the government's program: How often do border officers search travelers' cellphones and other devices, and for what reasons?

Why did the incidence of cellphone searches sharply increase in the past 15 months? Does the department follow its own rules for taking special measures to protect searches of privileged and other sensitive content stored on cellphones, and what are those rules?

The courts should require the government to disclose this information and quickly, and the practice of delving into travelers' private lives at the border without reason to suspect them of wrongdoing should ultimately end. Everything we know about the government's searches of devices at the border suggests the government is dramatically expanding an unconstitutional program.

Read more about the Institute's lawsuit for records relating to searches of devices at the border here.