The Government must make its voice heard over a landmark case before a federal court in New York, according to a lawyer for a leading US privacy advocacy group.

Microsoft has already been ordered by a judge to hand over emails held in servers in Dublin, allowing prosecutors in the drug trafficking case to entirely bypass the Irish-US mutual legal assistance treaty.

Microsoft, with support from other leading US companies, has appealed, with oral arguments set to be heard before a US district judge tomorrow.

Hanni Fakhoury, a lawyer with Electronic Frontier Foundation, called on the Irish Government to speak out. “I think definitely it could make its voice heard,” he said. “The Irish Government would want to say they cannot just trample on our sovereignty, cannot come up willy nilly on your own accord with out oversight... they cannot just walk in and get what they want.”

In the case, it is not known, at least publicly, the nationality of the target or where he or she is based. The ruling as it stands makes no reference to citizenship or residence, only that if a company is US-headquartered, then prosecutors have a right to demand and receive the information no matter where it is held.

If the ruling is upheld, prosecutors and investigators in the US putting together a case against an Irish citizen living in Ireland would be able to demand US firms hand over information regardless of where it is stored.

There are processes and procedures in place when seeking help from a foreign country to protect the privacy rights of Irish citizens and data stored in Ireland, Mr Fakhoury said.