That is indeed the case, at least in California. EMTs cannot declare someone dead -- they are "unconscious" until they get to a hospital and a doctor sees them. (Joss Whedon mentioned this in his commentary for the Buffy The Vampire Slayer episode "The Body" at the moment that the EMTs declare Joyce dead.)
Regardless of the legal requirements, it is apparently a widespread practice that a person hasn't officially died until a doctor "calls it". A case in point: my father died at 11:35ish PM on 5 May -- but his "legal" date and time of death is 1:30ish AM on 6 May, because that's when the doctor got to the house and played Captain Obvious.
-- Bob
---------
Then the horns kicked in...
...and my shoes began to squeak.
Regardless of the legal requirements, it is apparently a widespread practice that a person hasn't officially died until a doctor "calls it". A case in point: my father died at 11:35ish PM on 5 May -- but his "legal" date and time of death is 1:30ish AM on 6 May, because that's when the doctor got to the house and played Captain Obvious.
-- Bob
---------
Then the horns kicked in...
...and my shoes began to squeak.