According to the Wall Street Journal, the top three tech companies, including Google, Facebook, and Microsoft plan to file a joint motion that supports Apple's efforts to protect the privacy of its customers. Sources say at least one other tech company plans to be included in the joint brief as well.
In addition, BuzzFeed News is reporting that Amazon, Twitter, and Box are also planning to file briefs as well, but it is unclear if it will join the combined filing or file separately. The "friend of the court" briefs (amicus curiae) involve those who are not directly involved in a lawsuit, but have a strong interest in the matter and offers information that could influence the case.
The deadline to file this "friend of the court" brief is March 3, and Apple is surely expecting more support from other technology companies and privacy groups who have already expressed their interest in this case.