Fourteen of the biggest US tech companies filed a brief with the Supreme Court on Monday supporting more rigorous warrant requirements for law enforcement seeking certain cell phone data, such as location information. In the statement, the signatories—Google, Apple, Facebook, and Microsoft among them—argue that the government leans on outdated laws from the 1970s to justify Fourth Amendment overreach. One perhaps surprising voice in the chorus of protesters? Verizon.

Verizon's support means that the largest wireless service provider in the US, and a powerful force in Silicon Valley, has bucked a longtime trend of telecom acquiescence. While carriers have generally been willing to comply with a broad range of government requests—even building out extensive infrastructure to aid surveillance—Verizon has this time joined with academics, analysts, and the company’s more privacy-focused corporate peers.

Carpenter v. United States is “one of the most important Fourth Amendment cases in recent memory,” Craig Silliman, Verizon’s executive vice president for public policy and general counsel, wrote on Monday. “Although the specific issue presented to the Court is about location information, the case presents a broader issue about a customer’s reasonable expectation of privacy for other types of sensitive data she shares with any third party.… Our hope is that when it decides this case, the Court will help us better apply old Fourth Amendment doctrines to an evolving digital era.”

From the early days of landlines, telecoms have complied with law enforcement requests for customer data such as call length, location, and who has called whom. As the variety of data customers generate has exponentially expanded and evolved, so has this information gathering by government officials, often under a general mandate and without a case-specific warrant. For its part, Verizon cooperated with the National Security Agency as part of broad bulk surveillance programs for years. Details of this coordination was revealed in NSA documents leaked by Edward Snowden in 2013, but some aspects of it had been publicly debated for years prior.

Carpenter v. United States, which the Supreme Court will hear this fall, relates to the acquisition, without a warrant, of months of individuals’ location records by law enforcement officials in 2011. Officials looked back on 12,898 location records, spanning a four-month period, of one of these individuals, Timothy Carpenter, to build their case; Carpenter was eventually convicted. His appeal argues that location-data collection by law enforcement without a warrant violates his Fourth Amendment rights—and Verizon agrees.

“Verizon stands out because they actually hold the specific kind of location records that are directly at issue,” says Nathan Freed Wessler, a staff attorney at the American Civil Liberties Union, which represents Carpenter. “The telecoms have a long history in general of cooperating with law enforcement surveillance demands, but I think Verizon’s participation reflects a growing understanding of the importance of standing up for customers’ privacy rights."

As the general public becomes increasingly aware of the privacy risks associated with entrusting their data to corporate entities, a strong stance on data protection has been a boon to companies like Apple. This economic incentive may be even stronger for the numerous telecoms that now straddle the line between traditional utility and tech company. Verizon, for example, now owns Yahoo and AOL in addition to its role as a top-four wireless provider in the US.

"At the end of the day, a company like Verizon isn’t going to stick its neck out if it doesn’t think that there’s a business rationale in addition to it being the right thing to do," Wessler says.

Verizon has laid the groundwork for this move for months. Silliman wrote publicly last year about potential Fourth Amendment concerns when telecoms comply with warrantless law enforcement data requests. The company's stand won't necessarily prompt peers to follow—no other telecoms joined this particular brief—but it still represents a turning point in the dialog between privacy advocates and monolithic telecoms. And in Carpenter v. United States, it's only one of the voices that matters in the larger discussion about data privacy.

"The other tech companies bring the perspective that this case is also about our emails and our smart devices and all the kinds of cloud-stored data that we create in the course of our daily lives now," Wessler says. "The Justices should not be under the misapprehension that they can just try to narrowly apply these outdated precedents from the 1970s in this case. The implications are really huge, and this is the chance to make sure that our understanding of the Fourth Amendment keeps up with digital technology.”