Notes on the Viacom ruling

IP address is just like regular address in a sense - it's public, because you have to give it
to others in order to communicate with them, but it's private, because one can't store your
name and address without your permission. At least in Hungarian law, the definition for
private data is "data related to a person or data that could be used to draw a conclusion
about a person" (my translation from Hungarian legalese to English is probably not that good).
According to the Hungarian privacy ombudsman, the IP address is private data and according to
the law, private data can be transfered only if the person, whose data is affected, permits
this. 

However, I wouldn't draw the conclusion that this transfer of TBs of Google data would be
illegal under Hungarian law, because I'm not a lawyer.

The grey area is private as in secret, private as in personally-identifying and individual,
public as in not secret, public as in un-owned, public as in generally available.  I'm sure
there are more.  Which do you mean when you say "private" or "public"?  More, how do you
define secret?

Fingerprints: not secret -- left everywhere; private as in uniquely identifying and linked to
the person.  Personal in a permanent sense.  Not logged in a database by default, because the
assigning authority is unregulated.

Street address: not secret.  Anyone can find out addresses.  Temporarily linked to a
person/family (presumably for longer time values).  Not personal like fingerprints,  but a
unique identifier for the given domicile, and by extension the people living in it.  One might
argue a distinction between the address as such, public data, and the private association of
that address with a person, but in practice it is public-register information.

Telephone number: not secret.  Oh, you can unlist your number, making it harder to find, but
just like fingerprints, you leave it everywhere you call.  Besides which, the phone companies
and the government know it.  US courts have ruled, for competitive business reasons, that a
phone number, once assigned, is property of a sort, and may be retained across carriers.
However, while more personal because of that, it is still like the street address in being
hardware-defined, not user-defined.  In practice, it is still personally-identifying
information, with variable granularity in the case of landlines.

IP address: not secret.  More capable of being secured than street or phone system addresses,
provided tight routes and recipient and assigning authority are both secure and not talking to
anyone else.  However, most of the time you leave it everywhere you visit, and at every point
in between.  Assigned, just like the phone number, but with more variability.  For its
assigned span of time, unique to the hardware, not the user.  Just like street and phone, may
generally be assumed to be under the control of the person who is accounted owner of the
hardware or contracts for the service.

Now, any of these four may commonly be considered personal (YMMV based on jurisdiction and
laws), but your value of public ("you have to let people know what your IP address is to do
anything") is more properly "non-secret".  So, for that value of "private"="secret", nothing
truly is private.  Fingerprints are the only ones not logged on issue, and even that can be
changed, if your government decides to log your issue as they are born.  Someone else knows
your "private" information, if it is identifying, because true secrets have remarkably limited
ID potential by nature.

The fact that multiple users may be assigned to a piece of hardware, be it telephone/NID,
residence, or computer, makes those UIDs problematic as definite personal identifiers.  For
that purpose we have, in the US, SSN/taxpayer ID numbers and driver's license numbers, which
are user specific, not hardware specific.  Those the government has, and you have, and may be
secured by relatively simple expedients (on the user end -- your government screwing up should
not be discounted).

Be more specific, please, in discussions like this, and encourage your lawmakers to do the
same.

The term I tend to prefer is "personal data". Whether its secret or not is irrelevent. An IP
address could be used to identify you which makes it perfectly reasonable to place legal
limits on the distribution of that information.

It's on a need to know basis, and you don't need to know...