A legal ruling on whether the US government can force Microsoft to hand over emails stored on a server in Ireland relating to a drug-trafficking investigation is unlikely to be made before July, sources familiar with the case have said.

The technology firm is appealing against a US warrant demanding access to email on an overseas Microsoft account in a case that could have huge implications for privacy rights.

The ruling, which is likely to be appealed to the US supreme court, will determine how far US authorities can reach in order to obtain personal data and what powers companies have to guarantee the privacy of customer data held in their servers.

Despite reports the ruling was to be issued in February, the second US circuit court of appeals in New York is unlikely to deliver its judgment before July, a source told The Irish Times.