While large tech firms spend a lot of time at each other's throats, there are those occasions when they unite over a mutually beneficial cause - usually in the form of a joint amicus brief filed in court cases. It happened during Apple's battle with the DoJ, Donald Trump's immigration ban, and Microsoft's fight against US gag orders. Now, it's Google's turn to be supported in court, by Apple, Amazon, Yahoo, Cisco, and Microsoft.

The industry giants are backing Google after a Pennsylvania judge ruled the company had to comply with an FBI warrant asking it to hand over emails stored on a server overseas, according to Business Insider.

Google had originally refused the FBI's demand, saying it would fight the order, but the court is trying to force the matter. The search giant appealed the ruling last month.

"When a warrant seeks email content from a foreign data center, that invasion of privacy occurs outside the United States --- in the place where the customers' private communications are stored, and where they are accessed, and copied for the benefit of law enforcement, without the customer's consent," the brief states.

The companies say if Microsoft does hand over the data, it will "invite" other countries to demand emails from US citizens, which are stored on servers in the US.

"Our sister nations clearly view US warrants directing service providers to access, copy, and transmit to the United States data stored on servers located within their territory as an extraterritorial act on the part of the US government," the firms wrote.

A lot of the case involves the Stored Communications Act (SCA) and whether it can be applied to overseas data. The supporting companies claim the court judge is overstepping his boundaries by stating it is applicable. They say only congress can decide such matters.

Microsoft won a similar case in January when it refused to give up emails belonging to a foreign national that are stored on servers in Ireland. The US government appealed to have the case reheard, but its request was denied.