According to treaty it's the US embassy's responsibility to notify the Pakistani F.O. of a diplomat's status, not any court, and no further documentary proof is needed to establish such. That's all the U.S. needs to do. The whole idea of diplomatic immunity isn't to provide a diplomat with immunity from prosecution for criminal acts but immunity from a host country's jurisdiction. Davis can be pursued via a civil or criminal trial in U.S. courts - if the GoP makes the effort to do so.
"Raymond Davis is a US citizen and he was given a visa on the request of the US government" is what the F.O. confesses. The US government would not request that Davis be given a business or personal visa; it had to have been a request for a diplomatic or consular one. Under diplomatic immunity by treaty Davis, as an admin/technical officer, is immune from all Pakistani criminal jurisdiction, despite what the F.O. manual may say. Under the weaker consular immunity Davis can be held in prison under a murder charge - but the U.S. claims Davis has diplomatic immunity, not consular.
The LHC noted that the F.O. refuses to answer its questions. Why, then, aren't the relevant F.O. officials being held in contempt of court?
