The lawsuit may succeed despite losing the overt support of such big names. U.S. District Judge Derrick Watson in Honolulu on Wednesday ordered an emergency halt to Trump's executive order that aimed to temporarily bar entry to the United States of most refugees as well as travelers from six Muslim-majority countries. The halt is temporary.
Trump says the ban is necessary for U.S. national security, and called Watson's order "unprecedented judicial overreach."
Tech companies, which generally rely on skilled workers from overseas more than other industries, played a large part in the legal effort to halt the first version of Trump's executive order, which was put on hold by a Seattle judge in early February.
It was not immediately clear why fewer of them signed on to the "friend-of-the-court" brief this time around.
Companies will have an opportunity to join the effort as it moves through the court system, said Robert Atkins, a New York lawyer and co-author of the brief. "We do expect the group to expand."
Ride-hailing company Uber Technologies was in the process of adding its name, a spokesman said.
Box Inc, a file-sharing service, said that although it did not sign the brief, there had been no change to its position.
A Twitter spokeswoman pointed to past company statements opposing Trump's initial travel ban in January but declined to comment further. A spokeswoman for Facebook declined to comment.
Representatives of Apple, Google, eBay, Intel, Microsoft and Netflix did not immediately respond to requests for comment.