A hearing is scheduled for Sept. 17 in San Francisco federal court on the users’ request for a preliminary injunction. Trump’s order is due to go into effect Sept. 20 when the U.S. Commerce Department is expected to delineate exactly what transactions with the app, owned by Shenzhen, China-based Tencent Holdings Ltd., are prohibited.

The U.S. is arguing the group isn’t entitled to any evidence because the executive order has no legal effect on them and courts can’t review national security determinations by the president. Only the Commerce Department’s implementation of the order may be challenged, the government maintains.

According to the group, Trump’s Aug. 6 order would sunder the primary and often exclusive channel many U.S. residents use to communicate with family and friends in both China and the U.S. WeChat is also used to run businesses and non-profit organizations, practice religion and as a source news. WeChat is so integral to Chinese and Chinese Americans’ lives that a ban would be like “losing a limb” for some users, the group claims.

Separately, Patrick Ryan, a TikTok employee who sued Trump last month to block a ban on the video-sharing app under the same executive order, on Thursday asked for a preliminary injunction against the Commerce Department enforcing Trump’s order. TikTok employees don’t even know if they will violate the order, which prohibits otherwise unspecified transactions with the company, by showing up for work or accepting a paycheck, Ryan said.

“Plaintiff and other U.S. employees of TikTok are in imminent danger of losing their livelihood through governmental action that has no basis in fact, was politically driven, and afforded plaintiff no procedural protections,” Ryan said. “The 1,500 TikTok employees working in the US and their families will not be able to pay their rent or mortgages, or pay for food, medical treatments, and other essentials of life.”

The cases are: U.S. WeChat Users Alliance v. Trump, 20-CV-05910, and Ryan v. Trump, 20-CV-05948, U.S. District Court, Northern District of California (San Francisco).