About 15,000 from October to March, compared with 8,383 in the same period in 2015 and ’16 — agency officials said the latest numbers represent less than one percent of the 189.6 million travelers that arrived in the United States in that period.
“These searches, which affect fewer than one-hundredth of one percent of international travelers, have contributed to national security investigations, arrests for child pornography and evidence of human trafficking,” said John P. Wagner, a deputy assistant commissioner at Customs and Border Protection.
Privacy activists say the searches are invasive and violate Fourth Amendment protections against unreasonable searches.
But courts have long held that those protections do not apply at the border and at airports because of the government’s compelling interest in combating crime and terrorism.
A 2014 Supreme Court ruling did say, however, that law enforcement needed to have a warrant to search electronic devices when a person was being arrested.
“Modern cellphones are not just another technological convenience,” Chief Justice John Roberts wrote. “With all they contain and all they may reveal, they hold for many Americans ‘the privacies of life.’”
“The fact 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,” the chief justice wrote.
But since that case did not involve a search at the border, Homeland Security officials said the ruling did not apply to border searches.
Faiza Patel, a co-director of the liberty and national security program at the Brennan Center for Justice at the New York University School of Law, said she expected that to change.
“Lots of these exemptions to the Fourth Amendment were created when we weren’t seeing these kinds of searches of people’s personal devices,” she said. “I’m not sure that this can continue based on the way things are changing.”
The policy of searching cellphones and other electronic devices at the border started in the George W. Bush administration with a focus on specific individuals, but the searches have recently expanded to include broad ranges of people who do not pose a threat.
Joseph B. Maher, the acting general counsel at the Homeland Security Department, said searching electronic devices was the same as searching luggage.
“Just as Customs is charged with inspecting luggage, vehicles and cargo containers upon arrival to the U.S.A., there are circumstances in this digital age when we must inspect an electronic device for violations of the law,” Mr. Maher wrote last month in an op-ed in USA Today.
Last week, however, a bipartisan group of lawmakers on Capitol Hill introduced legislation that would require customs officers to get a warrant to search the contents of electronic devices at the border.
“By requiring a warrant to search Americans’ devices and prohibiting unreasonable delay, this bill makes sure that border agents are focused on criminals and terrorists instead of wasting their time thumbing through innocent Americans’ personal photos and other data,” said Senator Ron Wyden, Democrat of Oregon.
The bill was co-sponsored by Senator Rand Paul, Republican of Kentucky, and Representatives Jared Polis, Democrat of Colorado, and Blake Farenthold, Republican of Texas.
The border searches are also the subject of a lawsuit. The Knight First Amendment Institute at Columbia University is suing the Homeland Security Department for the details of searches of travelers’ electronic devices by customs officers since 2012.
The lawsuit alleges that customs officers and special agents with Homeland Security Investigations, a part of Immigration and Customs Enforcement, have seized and searched the electronic devices of thousands of people, including citizens, without suspicion — which it said could violate the Constitution.