U.S. border agents can search the laptops and smartphones of U.S. citizens for evidence of a wide range of crimes without first acquiring warrants, according to allegations made in two new court filings submitted Tuesday that are part of a lawsuit against such electronic searches.

Lawyers for the American Civil Liberties Union said new documents and depositions from Customs and Border Protection and Immigration and Customs Enforcement show that agents can search the electronic devices of travelers for “general law enforcement” purposes and communicate with other government agencies to search for evidence of crimes including tax evasion and hiding assets in bankruptcy.

The government argues that the “border exception” to the Fourth Amendment gives it wide latitude to search inbound U.S. citizens in the name of national security. Customs and Border Protection also maintains that the searches are legal and exceedingly rare.

Privacy activists maintain, however, that the rate of such searches has been rising in recent years.

“We are alarmed by the extent to which the government is using the pretext of the border to make an end-run around the Constitution,” Nathan Freed Wessler, an ACLU attorney, said in an email.

The September 2017 lawsuit, Alasaad v. McAleenan, filed in U.S. District Court in Boston, involves 10 U.S. citizens and one permanent resident who say that in recent years they were subjected to unlawful searches of their smartphones while returning home. The plaintiffs are represented by the ACLU, the ACLU of Massachusetts and the Electronic Frontier Foundation, a nonprofit that advocates for digital privacy rights.

The ACLU lawsuit aims to stop federal agencies from searching the digital devices of U.S. citizens at the border without a warrant. “Last year, CBP conducted more than 33,000 border device searches, almost four times the number from just three years earlier,” Wessler said. “That is not rare. But even if it were, it's still unconstitutional.”

A spokesperson for CBP said they could not comment on pending litigation.

The ACLU said that ICE agents asserted the authority to conduct warrantless searches of inbound travelers’ electronic devices for a variety of reasons, including targeting an “executive of a company suspected of criminally dumping toxins into a river, to find emails reflecting the illegal dumping.”

The plaintiffs’ attorneys asked the judge in the case, Denise J. Casper, to conclude that the agencies’ practices are in violation of the First and Fourth Amendments, to order federal agencies to stop the searches, and to delete any of the plaintiffs’ data that had already been seized.

“Warrantless and suspicionless device searches turn the border into a digital dragnet, where the government can search and retain troves of highly personal information about individuals — and their families, friends and colleagues,” Esha Bhandari, an ACLU lawyer, wrote in a motion for summary judgment.

In a statement in January 2018, CBP said that “less than one one-hundredth” of all international travelers were subjected to searches of their digital devices.

“CBP is committed to preserving the civil rights and civil liberties of those we encounter, including the small number of travelers whose devices are searched, which is why the updated Directive includes provisions above and beyond prevailing constitutional and legal requirements,” John Wagner, deputy executive assistant commissioner of the Office of Field Operations for CBP, said in the statement.

“CBP’s authority for the border search of electronic devices is and will continue to be exercised judiciously, responsibly, and consistent with the public trust.”

In a March 2017 investigation, NBC News examined 25 cases where American citizens said that customs officers at airports and border crossings demanded that they hand over their phones and passwords, or unlock them. The practice grew noticeably from 2015 to 2016, according to U.S. officials. While the Fourth Amendment protects against “unreasonable searches and seizures,” there has been a longstanding loophole known as the border exception, which allows the government to conduct searches without a warrant within 100 miles of the border in the name of national sovereignty.

U.S. courts have wrestled with the question over how to balance the privacy Americans expect over the content of their cellphones with the government’s legal power to conduct searches at the border.

In a landmark privacy case from 2014, Riley v. California, the Supreme Court ruled that searching cellphones during an arrest without a warrant is unconstitutional because the devices are fundamentally different from other types of containers that people carry, like a bag or briefcase, for example, because of the many kinds and volume of data they contain.

However, an appellate court found last year that the Riley precedent did not protect a child porn suspect who had his three cellphones searched and seized at the U.S. border.

Judge Casper has scheduled a hearing in Alasaad for July 18.