"Respect Irish sovereignty," Ireland has told a court that is hearing a dispute over access for U.S. law enforcement to email communications held by Microsoft in Dublin.

"Ireland respectfully asserts that foreign courts are obliged to respect Irish sovereignty (and that of all other sovereign states) whether or not Ireland is a party or intervener in the proceedings before them," according to an amicus curiae (friend of the court) brief filed Tuesday in the U.S. Court of Appeals for the Second Circuit.

Microsoft is appealing a search warrant in the U.S. for private email communications located in the company's facility in Dublin, arguing that U.S. law does not allow the government to issue search warrants to obtain customer data stored overseas.

A key issue in the case has been the interpretation of the warrant. U.S. Magistrate Judge James C. Francis IV of the U.S. District Court for the Southern District of New York held that a warrant under the Stored Communications Act was "a hybrid: part search warrant and part subpoena."

It is executed like a subpoena in that it is served on the Internet service provider that is required to provide the information from its servers wherever located, and does not involve government officials entering the premises, he noted.

"The warrant at issue operates as the exercise of U.S. law enforcement authority on Irish territory, something that can be done only with the consent of the Irish government," Microsoft General Counsel Brad Smith said in a blog post Tuesday.

Ireland is citing a mutual legal assistance treaty with the U.S. that law enforcement can use to obtain the email. In its brief, Ireland said it "would be pleased to consider, as expeditiously as possible, a request under the treaty, should one be made."

"The right of individuals to the protection of their personal data is an essential foundation for modern society and the growing digital economy," said Dara Murphy, Ireland's minister for data protection, ahead of the filing. "We must ensure that individuals and organisations can have confidence in the rules and processes that have been put in place to safeguard privacy."

A number of tech companies have supported Microsoft with legal briefs including Apple, Amazon.com, AT&T and Verizon Communications. The concern among these companies is that the U.S. government's demand for data held abroad could spook customers abroad from their cloud and other services, besides violating international agreements. The Department of Justice has argued that by Microsoft's interpretation of the law, email providers could move content around the world to avoid law enforcement requests.

John Ribeiro covers outsourcing and general technology breaking news from India for The IDG News Service. Follow John on Twitter at @Johnribeiro. John's e-mail address is john_ribeiro@idg.com