From hushmail's website:
What if Hush receives a court order to release the contents of my account?
Hush Communications maintains its servers in British Columbia, Canada. Hush Communications complies fully with valid court orders issued by the courts of British Columbia, Canada. In order to ensure consistent treatment of all users, Hush Communications does not accept court orders from other jurisdictions. However, law enforcement agencies from other jurisdictions may pursue action through international channels compliant with the laws of British Columbia and Canada, resulting in a court order being issued by a court of British Columbia.