Google was issued a search warrant in July last year to turn over the material in question, which was sought in connection with a US federal investigation into wire fraud.
Google contested the warrant, citing a case where a court had ruled that Microsoft did not have to hand over emails stored on a server in Ireland, because US warrants did not have jurisdiction over material stored abroad.
The storage of commercial data in the US has come into focus after the revelations by former NSA contractor Edward Snowden that the NSA was conducting blanket surveillance of all data in the US. American companies have lost business from foreign entities as a result.
This has led to American tech multinationals making a bid to assure their foreign clients that their data is safe from snooping; in Microsoft's case, it even set up cloud services in a German data centre in March 2016 to avoid being subject to US laws.
In the Google case, US Magistrate Judge Thomas Rueter ruled against the company in February, saying that copying email from a server based outside the US — so that FBI agents would be able to see them as part of an investigation — could not be considered a seizure. Gogole's bid to have the warrant quashed was thrown out in April.
In its response to the DoJ's request to Justice Seeborg, Google said that it was not obeying the February decision because it had made an appeal against it. A second reason cited was the decision in the the Microsoft case.
Google's appeal has been made to the San Francisco-based 9th US Circuit Court of Appeals. But both Justice Seeborg and the 9th Circuit are not bound by the Microsoft decision which was handed down by the 2nd Circuit Court of Appeals.
Circuit courts of appeal do not have to follow rulings by each other. However, the Supreme Court's precedents have to be followed.
"Google will continue to preserve information in its possession that is called for by the warrant but stored outside of the United States, and would immediately produce this information if, after exhausting its appellate options, it does not prevail," the company wrote.
In its submission to the court, the DoJ pointed out that Google had made no move to determine whether any of the emails sought in the warrant were located outside the US until the Microsoft verdict was handed down on 14 July 2016.
"That very day, Google placed a 'moratorium on the processing of all search warrants, in response to the Second Circuit Decision', which included the warrant at issue here. Google at this point neither produced any responsive information nor did it seek an extension or other relief from the issuing magistrate judge," the DoJ said.
The US Supreme Court is expected to announce soon whether it will hear an appeal by the government against the Microsoft verdict. The petition to the court was made in June.