Megaupload and the US grand jury

Megaupload again: according to the US Justice Dept, Dotcom, Batato, Bencko, Echternach, Ortmann, Nomm and van der Kolk were indicted by a grand jury in the Eastern District of Virginia on January 5 this year. Megaupload and Vestor Ltd were also included in the indictment, and it's on the basis of that that the NZ police pulled out all stops to raid Dotcom's Coatesville house and to arrest him and associates.

Obviously, grand juries are powerful entities if their indictments are sufficient to trigger full-scale police actions overseas. What are they though? From what I can tell, grand juries go back to the middle ages. Today, only the United States retain grand juries, and not all states have them. New Zealand abolished grand juries in 1961 but the Fifth Amendment of the US Constitution requires grand jury indictments for federal criminal charges still.

The American Bar Association seems like a good place to find out more about grand juries and its FAQ page on them is interesting. The general idea is that grand juries review evidence presented by prosecutors and determine if there's a probably cause to return an indictment like in the Megaupload/Dotcom case.

That sounds fine, but reading on, the ABA is actually very critical of the grand jury system. Here are some of the points the ABA makes:

• There is no need for a grand jury to hear all the evidence, or conflicting evidence.
• Grand juries have wide, sweeping, almost unrestricted power.
• This power is virtually in complete control of the prosecutor.
• Jurors are not screened for biases or other improper factors unlike jurors in regular trials.
• Grand jury proceedings are secret, hears cases brought to it by the prosecutor who in turn decides which witnesses to call.
• There is no judge in the grand jury room, nor lawyers for the witnesses. Grand juries are rarely read any instructions on the law, as there is no such requirement.
• The accused has no protection against witnesses lying to the grand jury, or against evidence obtained "unconstitutionally".

Critics of the grand jury system say it simply acts as a rubber stamp for the prosecutor, according to the ABA.

Dotcom and Megaupload will apparently have the opportunity to argue their case and refute the evidence that the grand jury based its indictment on in a trial. Even if they defend themselves successfully, surely it will be too late as the Megaupload business is in ruins, Dotcom and others will have spent many months in prison and been extradited to the US.

I'd be interested to hear from legal people on this, as to me a grand jury indictment could potentially be a little less robust than expected. Should New Zealand really raid someone and seize their assets based on grand jury indictments? Am I missing something here as a layman?