The justices left in place lower court rulings against the Israeli firm, NSO Group. WhatsApp claims that NSO targeted some 1,400 users of the encrypted messaging service with highly sophisticated spyware.

WhatsApp parent Facebook, now called Meta Platforms Inc, is trying to block NSO from Facebook platforms and servers and recover unspecified damages.

NSO argued that it should be recognized as a foreign government agent and therefore be entitled to immunity under US law limiting lawsuits against foreign countries. The request appeals a pair of earlier federal court rulings that rejected similar arguments by the Israeli company.

The Biden administration recommended that the court turn away the appeal. The Justice Department wrote that “NSO plainly is not entitled to immunity here.”

NSO’s flagship product, Pegasus, allows operators to covertly infiltrate a target’s mobile phone, gaining access to messages and contacts, the camera and microphone and location history. Only government law enforcement agencies can purchase the product and all sales are approved by Israel’s Defense Ministry, NSO said. It does not identify its clients.

WhatsApp says at least 100 of the users connected to its lawsuit were journalists, rights activists and civil society members.

NSO said it has safeguards in place to prevent abuses, although the company also said it has no control over how its clients use the product.

The WhatsApp case is among a series of legal battles plaguing NSO. In a separate lawsuit, Apple says it aims to prevent NSO from breaking into products. It claimed Pegasus had affected a small number of iPhone users worldwide, calling NSO’s employees “amoral 21st century mercenaries.”

NSO also has been blacklisted by the US Commerce Department, limiting its access to US technology. US officials said the company’s products were complicit in “transnational repression.”