Apple, Facebook, Microsoft, Twitter and other tech companies filed an amicus brief tonight voicing opposition to President Trump’s executive order on immigration on the grounds that it is discriminatory and has a negative impact on business.

The companies filed their brief in a case brought by Minnesota and Washington state, which challenges Trump’s executive order. The Trump administration appealed the case to the 9th Circuit after a federal judge in Seattle halted the immigration ban. Trump attacked U.S. District Judge James Robart in a series of tweets over the weekend. “The opinion of this so-called judge, which essentially takes law-enforcement away from our country, is ridiculous and will be overturned!” Trump wrote. “Just cannot believe a judge would put our country in such peril. If something happens blame him and court system.”

The filing, first reported by Bloomberg, follows a week of outspoken comments from tech industry leaders against the immigration order which barred refugees from entering the United States indefinitely and temporarily restricted travel to the U.S. for citizens of Syria, Iraq, Iran, Yemen, Libya, Somalia and Sudan. A challenge to the president’s order has reached the 9th Circuit Court of Appeals in San Francisco, and the companies intend to file their brief in this case.

Prior to the official filing of the brief, Twitter and AppNexus confirmed their participation in the amicus brief to TechCrunch. Sources with knowledge of the filing confirmed the participation of Uber, Airbnb, Yelp, Square, Reddit, Kickstarter, Github, Mozilla, Dropbox, Twilio, Netflix, Zynga, Salesforce, Lithium, General Assembly, Pinterest, and Medium.

The full list of companies is as follows:

Executives from many of the companies involved have spoken out against the immigration ban, with Airbnb launching a Super Bowl ad campaign emphasizing inclusiveness with the hashtag #weaccept.

Several of the companies have said their employees are directly impacted by the ban, and Uber has created a $3 million legal defense fund for drivers affected by the ban. Uber’s CEO Travis Kalanick was set to attend a meeting of Trump’s business advisory council on Friday, but stepped down from his post on the council Thursday evening after blowback from users and employees about his participation.

The amicus brief, which argues that Trump’s immigration order is illegal, highlights the contributions of immigrants to the tech economy while stressing the immigration controls already in place. The companies argue that Trump’s order is discriminatory and will have a negative impact on American businesses. The brief states that Trump’s immigration policies will make it more difficult and expensive for companies to hire new employees from around the world, and will make it more difficult for companies to conduct business because of travel restrictions on their employees. The companies also argue that the discrimination enshrined in the order will trickle down to the companies themselves — if job applicants can’t travel to the United States, companies might be forced to discriminate against them, the brief claims.

The brief describes previous immigration laws that were later overturned, such as the Literacy Act and the Johnson-Reed Act. “The march of time has discredited these laws and policies,” the brief states.

The filing criticizes Trump’s administration for rolling out the ban haphazardly, with little notice to the Department of Homeland Security and other enforcement agencies. It argues that the order is confusing by design and that the confusion caused by it will only grow. The ultimate result, according to the companies, is that skilled workers will no longer seek employment in the United States.

“Skilled individuals will not wish to immigrate to the country if they may be cut off without warning from their spouses, grandparents, relatives, and friends — they will not pull up roots, incur significant economic risk, and subject their family to considerable uncertainty to immigrate to the United States in the face of this instability,” the brief says.

A draft of the amicus filing obtained by TechCrunch stressed the importance of open borders. “The experience and energy of people who come to our country to seek a better life for themselves and their children — to pursue the ‘American Dream’ — are woven throughout the social, political, and economic fabric of the Nation,” the draft stated.

Notably absent from the list of 97 companies are several who met with Trump prior to his inauguration: Amazon, Oracle and IBM. Oracle CEO Safra Catz is serving as an advisor to the Trump transition team.

Update2/6: An additional 31 tech companies joined the brief today, including SpaceX, Tesla, Slack, and Zendesk. Tesla and SpaceX CEO Elon Musk has defended his decision to remain on an advisory council for Trump.

Amazon is listed as a witness in the Washington lawsuit brought against the ban, and a spokesperson for the company said the Washington Attorney General advised Amazon not to sign the amicus brief because of its status as a witness.

If the 9th Circuit finds Trump’s ban illegal, it’s likely his administration will continue to appeal and the case could reach the Supreme Court.

This story has been updated throughout to reflect the official filing of the amicus brief. An earlier version of this story stated Amazon CEO Jeff Bezos had not publicly opposed the immigration ban; Bezos did oppose the order in an email to employees.